Torchlyte said:It's hard to come up with fortress layouts and guard routines on the fly... for me, at least.
Granted, it can be tough at times, but the OP has mentioned a very fertile source of inspiration for this very thing - the Thief video games. Go back and reread the part in the DMG about borrowing liberally for your campaigns. Seems to me that once again, the solutions are right in front of him. If you're able, go back and play the games for a few hours. Get a feel for what the environments look like and how the NPCs are placed and move around. It's been long enough since they've been out that if you dress the scenarios up with D&D flavor, and with the shift to team-oriented play and the opportunities of roleplaying instead of being on a linear path, your players probably won't even notice, and if they do, they'll probably enjoy it just as much.