The Green Room is a space that is created and set aside for program participants.
Program participants are invited to meet in the Green Room before panels in order to meet and plan their program item. (The name comes from live theater and historically refers to the room that actors use to prepare in and retire to when they are not on stage during a show.)
Some conventions give their concom and staff access to the green room as well, or offer a separate staff lounge. But you needn't do either. There are also Regional and Genre convention variations, for example Filk cons never have a Green Room.
Green Room is usually a quiet social space, typically located in a hotel or convention center conference room. Sometimes a guest room is used so that food and drink can be served there without having to pay corkage fees, pay for catering, or negotiate a corkage waiver for function space. However, there are trade-offs with using sleeping rooms; if the Green Room location is not in the immediate area of programming function space, program participants are less likely to come there for panel prep because of the extra time needed to get back and forth to programming. If elevators are scarce and Green Room is on a floor remote from main program, this is especially true. On the other hand, when using function space, negotiate with the hotel if you wish to provide food or drink. First choice is generally to get the corkage waiver in your hotel contract to cover the space your Green Room will occupy, so that the convention may provide its own snacks and beverages without incurring an additional charge. Check with your hotel liaison about this possibility early in the hotel negotiation process. If corkage waiver is not an option, consider using some of your convention's contractual catering budget to cover the cost of providing tea and coffee service, at a minimum. If one is discreet and tips the service staff generously, it is also often possible to "supplement" hotel-provided catering with the convention's own supplies without incurring a corkage fee. Be nice to your banquet captain and your banquet captain will be your friend.
If Green Room is to be in a sleeping room or suite, a few extra tables (and extra tablecloths) from the hotel can be very handy. If the hotel is willing to remove beds, dressers, and other extraneous furniture from the room and replace them with spare couches or comfortable chairs, that's useful too. This is worth touching base with your hotel liaison early in the negotiations process about to see what is possible. Arrange with housekeeping for extra towels for the bathroom, they are very useful for clean up, but bring your own well-stocked hospitality kit, including trash bags, paper towels, sponges, spray cleaner, dish soap, dish towels, prep knives, cutting boards, and serving dishes and utensils, if you plan to provide any food beyond individually pre-packaged snacks.
When organizing furniture for a function-space Green Room, it's good to provide flexible seating options. A mixture of large and small round tables (again with associated table cloths) with banquet chairs to go around is a good starting point, with several 6- or 8-foot tables around the periphery for catering and also for Green Room staff and supplies, registration table (if any), and Program Ops if they are operating out of the Green Room. Additionally, if you can get the facility to provide a few couches and comfy chairs and coffee or side tables to go with them, that is ideal. You should also make sure that the room set-up includes at least one small trash can for each staffed table in the room, and at least one large garbage can and extra liner bags if you are doing any food service.
Green Room Hours typically run from at least 1/2 hour before programming begins each day until the beginning of the dinner hour (or until it's time to pack up on the last day of the convention), though hours may be extended if there is late-night programming. Late Friday hours may be necessary if program participant check-in is hosted in the green room. Even if there are late hours, however, the green room is often closed during dinner on Saturday when the banquet is usually held (approx. 6 pm to 8 pm, depending on the program schedule).
Staff your schedule deeply enough so that individual staffers can get out and see some of the con. Don't forget to have enough staff to allow for emergency shopping runs and re-stocking catering supplies or food prep if you are serving food.
Levels of service
The primary purpose of a Green Room is to allow panelists to meet and prepare for their next event. To that end it's a good idea to provide some tools to aid the process. Having several small writing pads, pens, and even hi-lighters available at every table is helpful for panelists who want to make notes and organize them. Spare tent cards and markers to make new or corrected name cards are useful to have on hand. Other potentially useful items include index cards, a flip chart and flip chart markers or white board and dry erase markers and, if your facility permits it, blue painter's tape to tape up flip chart pages. It never hurts to have a stapler and some paper clips on hand, either. If you can arrange to have free wifi in the Green Room, that will be appreciated by wired panelists. Having a laptop set up for guests who need to access the internet is a nice bonus if you can arrange it.
A secondary purpose to the Green Room is providing a space for panel participants to relax and socialize. Philosophies and budgets differ on what level of catering is necessary to support that goal. Refreshments vary from coffee and tea service only up to deli trays, hot foods, and cocktail shrimp. While it is nice to make program participants feel refreshed and maybe a little bit pampered, you should keep in mind that all convention members (ideally) contribute to the convention. You should be able to justify whatever differences there are between Green Room offerings and those of the Consuite. One justification for providing some more substantial food would be if you have heavily programmed panelists who do not have time to get restaurant meals between panels. Another justification may be catering to dietary needs of your Guests of Honor; check with your guest liaison, or directly with the guest if there is no liaison.
It need not be expensive to offer some more nourishing food options. Soup and hard-boiled eggs are two popular items to cook in advance. Homemade baked goods, sandwiches, cold cuts, crudité platters, cheese plates, are other possibilities. Do make sure that all foods, especially the home-made ones, are well labeled regarding ingredients that could be allergens. It's also good to make it clear which prepared foods are vegetarian, and which are not. Check in advance on your state's Health Department food service regulations; it may be necessary for anyone serving food to get a food handler's card.
In addition to refreshments, Green Room may provide a variety of amenities including newspapers, card decks, social, board, or card games, a coloring and sticker station for decorating badges, puzzles, Lego, or whatever amusements your budget and imagination allow. Penguicon provides a massage chair and qualified massage therapist, for instance.
Like the Consuite, a sleeping-room Green Room must follow the Hotel's rules and regulations. Hot plates, toasters, portable stoves, etc. may be verboten. Crock pots, microwaves, percolators and electric kettles are generally allowed, but check with your hotel liaison to be sure you know what's permitted in the contract. It's also a good idea to check with a hotel engineer to find out what kind of load the room's electrical circuits can support and then check that against the wattage draw of any appliances you plan to use. It is perfectly possible to blow a hotel room circuit by running two electric kettles, or one electric kettle and a microwave, at the same time, and many hotels charge a hefty fee to re-set a circuit. A small refrigerator is very handy, and can sometimes be requested in advance through the hotel, though you can make do with a cooler or two. And of course there's always the bath tub full of ice for chilling beverages. It's a good idea to check in advance what the hotel charges for delivering ice as a convention may put too large a strain on the ice machines to keep up with your hosting needs.
For a larger operation, it may be possible to find a free, full-size fridge from Craigslist. You don't care that it's a power hog since you're only running it for the weekend, but again, check on the draw compared to the load capacity of your room's circuit. You may need to buy a high-capacity coffee maker (check your local rental store), but other equipment can often be borrowed.