one thing to be careful about is making sure each floors are very distinct so the players can easily orient themselves. (I understand it's very early but your last screenshot suggests a lot of copypasting) you may find it difficult to make every area have a strong sense of purpose if they all offer similar/repetitive gameplay. it's part of what makes buildings tricky in level design.Here they are. About 6 or 7 in total, and I didn't want to make my post look too huge.
I'm working on something of an office building where both red, and blu enter, and go at it. I'm eventaully going to put in some windows that will be open so that smart enough soldiers, scouts, engineers, demos, or etc can skip a floor or two, but it will be high enough so that they'll take a lot of damage.
Also eventually I will figure out the skybox so I won't have to stare at brick walls everywhere, or dev. textures.
Ultimately I decided to use teleports to make an elevator I guess I'll put down something better than arrow decals later on. I was going to do an actual elevator, but they seem to be problematic, and generally are a pain in the butt. Teleports aren't perfect either, but it's better than nothing.
as for teleports/elevators/ladders, I find they're all uninteresting ways to traverse vertical space gameplay-wise as they usually constrain player movement. it's good that you are planning a couple alternatives (windows and such) but you need to make sure to not divide the team too much by funneling different classes into different paths (or at least you'll need to figure out areas where teams can regroup). If the lower areas only get used by medics and heavies, you may have messed up as class diversity is part of what makes tf2 fun.
it's a lot of things to consider, but no one said making tf2 maps would be easy.