Didn't do any of the rides, mostly because I was running low on time and wearing a suit, but this review covers the tower and the observation deck itself.
It basically boils down to this:
Are you a guest of the hotel? Yes? Then definitely come on up, because it's free. Going to Lounge 107? Get your free pass and come on up. Going on rides? Get the deal that includes all of the tickets and come on up.
Are you just coming up for the views but aren't a guest of the hotel? Forget it and go somewhere else, your twenty dollars are better spent elsewhere.
Nothing against the tower. The views are wonderful, both night and day, but the price is simply too much if you are just getting a good view. There honestly isn't a whole lot to look at besides skyscrapers, desert landscape and mountains. However, I did find it a great spot to do research for the day when trying to find events going on, since there are plenty of tables and chairs to sit on. Otherwise, your twenty dollars can take you much further somewhere else.