Michael, I did see a couple of people with tripods while I was up there, but I'm not too sure how effective they would be. The entire observation platform is enclosed in a "wire cage", and you have to shoot through small rectangular shaped "portholes". They are so small, that my 17-35 lens would not fit through the opening. So, you would have to sort of lean the tripod forward, to get the lens up against the opening. Also, it is a fairly small walkway, so you would have to be very aware of other people walking past. It might work, but there is some vibration in the tower from the wind, and people walking around the platform.
I agree, that the Stratosphere is terrible for taking pictures. The view is just too obstructed. Back in 2007, I was up there during the day, when someone decided to end their life, and
jumped off. Not a very pleasant way to start a vacation...