I guess I should disclose that I got to take the Tower tour (self-guided) for free as one of my friends is an employee at Stratosphere.
I think the cost is around 12 or 14 bucks, you have to go through a metal detector/security check point before you're allowed up the elevators. You can also take a picture against a green screen and after your tour they will photo-shop you against a spectacular Vegas backdrop. For an additional cost of course.
Still, I think it's something to "try" at least once. If you are not good with heights, this obviously is probably not something you want to try. The elevators go up and down incredibly fast so you'll definitely feel your ears pop a few times. There are a few shops and places to get food or drink up at the time, as well as an artist that can sketch a caricature of you if you pay them.
The view is magnificent and goes 360 degrees around, lots of great photo ops. There's even patio area where you can walk outside if you don't want to take pictures through windows.
There are also a few rides that you can go on that look ridiculously frightening.