I am going to Vegas for the Super Bowl - it will be my 4th trip to Vegas in 12 months. Poker is my hobby and it is about all I do there anymore.... I usually just go with friends (my wife doesn't care I go)....
I don't really see shows anymore but I have seen 3 Cirque shows and they were all fantastic. I don't want to see any that I have not seen as I heard they are not as good.. I have seen O', Mystere and Ka... all area great (Belagio, TI and MGM)....
You can also just spend a week walking around the strip and seeing all the hotels..... I have been 7 times in the past 2 years and have not set foot in Monte Carlo in that time frame for example..
You will likely want to go downtown and see "Old Vegas" - Fremont street... There is a zip line you can ride there now - and a night light show that is of course free.. going up top of the Stratosphere is cool and worth it - there are also three rides up there you can ride (I would be scared poopless to ride them).
You can go to the top of the Eiffel Tower (I have eaten in the restaurant but never going to the top).
One of the world's largest auto collection is at The Quad (Imperial Palace).... you can find buy one get one free coupons - think it is like 10 bucks.. I have never been but heard it is worth it....
You can check out Gold and Silver Pawn (Pawn Stars) - I have been once and was not impressed.. I went looking for a nice Gibson Les Paul - and they didn't have squat. 1/2 their store is now devoted to selling t-shirts for the show.
Hoover Damn is not far away - and neither is the Grand Canyon (never been there)...
I do want to go to the Grand Canyon Skywalk -
http://www.grandcanyonwest.com/
Tons of great places to eat too - can be really pricey, but you can find deals if you are tight and willing to shop around.
BD