i too know of nothing canon. and each level should be a bit different. since for example, i doubt a room as big as the gateroom extends all the way up to the surface...or at least level 11.
what i do know for sure is what's on diff levels
level 11 is where they change elevators and the implied beginning of the sgc(like norad has levels 1-10 and the sgc is 11-28)
security offices are on level 16, along with detention cells and an escape hatch to the surface(though putting an escape hatch on the same level with cells just doesn't seem like a good idea to me)
Level 19-Rothman’s lab
Level 21- Sam’s lab, infirmary
Level 22- isolation rooms
Level 23- where victims of the aliens were kept(foothold, so there's a big room there)
Level 25 - VIP Quarters
Level 27- armory
Level 28- where the stargate and control room are kept(briefing room maybe. It is either on the upper half of level 28 or level 27. Hammond’s office is adjacent to the briefing room)
this isn't to say there might not be multiple armories or isolation rooms or vip quarters on diff levels, this is just where they've been showed to be.
then again when season 5 starts the show folks might forget any of this and do something else
and in singularity sam makes a mention of the test she'd doing taking place in a lead lined room in a sub-level...though i dunno how much more sub you can get than 28 stories under a mountain.
