Okay so:
Main Cell Area
Just your basic ass main cell area. Get a two-floor cell building in there with at least 10 cells in all (maybe more), five on top, five on the bottom. Should be kind of large, but not too large where it takes too long to get to a certain area and not too small where it feels cramped.
Armory
I feel like it should only have the basic T and CT weapons (AK, M4A1-S/M4A4, USP-S/Glock), with a couple of the outlier weapons in there (UMP, MP9) and of course the AWP.
Games
A room with Soccer should be in there (imo it should be medium sized, not as big or bigger than the soccer field on space_jail), along with an LR Room (which should contain areas that go hand-in-hand with the most prominent LRs like S4S, Deagle Toss, and Knife Fight) and a Deathgame Room (which should contain an area that go hand-in-hand with DGs such as Simon Says, Climb, Maze). LR Room and Deathgame Room should be next to each other imo.
Medic
Just a basic medic. Rows of beds with the healing part being generous, but not too generous so that it won't be as OP. Shouldn't be as cramped, allows prisoners to flow freely.
VIP
I don't know what to say about VIP except make it a part of the Main Cells. Should be a spacious room in order to make it feel like you're a VIP. Maybe add some bathrooms with a hidden item in there. I recommend using the Disco on sg_dojo as a good example. Don't know if you wanna add Disco to VIP or not. Your choice.
Cells
Should make them feel cramped, imo. Make them feel like they're cells that you would find in an actual prison. At least 2-3 cells should contain a weapon/item (USP-S, Glock, Smoke Grenade, HE Grenade, and Flash Grenade are my suggestions). For furniture, I would just stick with a basic bed. Nothing else. Maybe add a vent that leads to somewhere like Disco or Top of Cells. Teleporters to some of the General Purpose areas would be nice.
General Purpose Rooms
Obviously gonna need a Kitchen and a Pool (with showers right next to them). As said above, Idk what you wanna do with Disco, but if you're gonna add one, make it so that it contains iconic songs from some of the other maps (dojo and mountaincraft are OK examples. Would recommend meme songs such as
or the original glue70 - casin). Iso would need to be cramped AF, maybe put it near Main Cell Area.
Sorry if I sound like a neo-fashionista. I like putting some designs together lol. I dunno what you guys might think up, but I just wanted to post my ideas here. Might edit it later on.