Are you talking about converting a room into a giant bearded dragon enclosure, or just using a room to put more/bigger enclosures in? Here's what I would do for either of them:
Room as a giant enclosure: This seems like it would be a cool experiment, but I don't think I'd ever really try it. Just the same, if I did, I would do it like this. I'd probably have a window in the door to the room so I can see what they're all up to without opening the door, but whether or not I did, I would also have a plexiglass and wood structure that would be about 3' feet tall and basically just be a horseshoe shape (except more square) around the inside of the door, giving it enough room to open into the room without possibly harming the beardies. Furnishing would be hard, because sand would obviously not be the substrate of choice....maybe a lot of shelf liner or something? You could go with covering the whole room with soft indoor/outdoor carpetting, but that would be much harder to clean than having sections of it or something else. I'd turn one corner into the high basking spot....with some sort of structure for them to climb on and heat lamps hanging from the ceiling or from something protruding from the wall (they would probably be mercury vapor bulbs, because it would be much harder to get big flourescents down that low...though there would also be some normal flourescents in the ceiling so the room would be bright. I'd have the adjacent corner be another basking spot, either the same temperature or slightly lower (depending on how many dragons I would have). This is a little wasteful, but as long as it's not the room where the thermostat is, I would leave all of the heating and air conditioning on in that room just to keep the temps right year round. Either that or I would have some sort of thermostat system in the room. Besides that....some nice hides and branches....and some plants to make it look cool. Maybe a big water bowl for them to swim in, but I'm not sure. By the way, for this setup I would still only house one male to many other females, and only around breeding season (if I were to breed).
What you probably were talking about was just having a room with many different enclosures? If you were, what I would do is find (or build) some really nice enclosures....since you have the room, go with 4'x2'x2' for single beardies (like males, outside of breeding season)...and something like 6'x3'x whatever height you want (probably 2'). Make sure these are the cages with built in lighting that you can stack up...so front opening is a must. Once you get all of the cages, determine how much of the room they will take up and determine if you will expand your collection in the near future. If no, and you end up with a lot of open room, maybe do some decorating? Potted plants (that are non toxic), wall decorations...maybe paint the walls.
Just some ideas I had if I were personally going to do either.