If you are staying on the Strip or on the 'New Vegas' side-take a bus (the bus passes are very economical and run all the time-the ticket machines are by the bus stops) and go to 'Old Vegas'.
DH and I had a blast in 'Old Vegas', it was campy, a little corny and what we pictured in our mind when we think about Vegas-the Golden Nugget (Bingo Hall was a hoot), the older casinos, the music/video show across the 'ceiling' of the street-tons of fun! We even played Keno at some cafe while we ate, the hostess brings around Keno cards.
Another thing we did that was fantastic-we booked a tour of the Hoover Dam-AWESOME! They pick you up at your hotel, take you to the Dam for the 'Dam Tour', if you have never been out west (it was our first time), the desert and the sky are so perfect they look fake. I don't remember what it costs, but I thought it was reasonable.
For shows, we saw 'Phantom' which we both loved and a Cirque show-the nude one-which was very good and definetly for adults only. We also had lunch at Paris and ate in the Eiffel Tower, the tables for two are a few stories up, against the glass so you look out onto the strip, we were right in front of the Bellagio Fountains.
Have fun!