The High Roller is the world's largest observatory - a full 550 ft high. That's about 100 ft higher than London Eye. It has two prices depending on whether you go day (cheaper) or night. Regardless you get a nice 360-degree of Vegas. Keeping you company is a virtual tour guide who's actually funny and not too annoying.
We came here in the afternoon and got our own cabin. It's a fun experience and worth trying once. It moves real slow and is not intimidating, even if you don't like heights.
Also cool is the entrance with various Halloween-themed puppets and a real cool launch pad room that simulates a night-club environment.