The Hancock Observatory and Tower was a wonderful attraction to see. It is best to go on a decent day with some visibility.
You have to wait in line for a fair amount of time, before you get brought up to the top of the building. So it may not be a bad idea to try and research when the best times to go are where it's not so busy.
You get to listen to headphones during the tour, but i will keep it a secret on who is narrating the city and it's highlights for you.
I highly recommend going to see this. It is only a couple hours max!

This is a must-see. The views are spectacular. Watching the sun go down and the city lights appear is incredible. They now have a headphone/audio presentation which is interesting.

Great views from all four sides of the 94th floor. The guided audio tour narrated by David Schwimmer added a lot to the experience. We went on a Friday in August in the mid-afternoon and the wait for the elevator was not bad at all.

great view, very good audio options!
We were lucky and came on a day with very few people, made it a great view and easy to see all we wanted.