Check out this site, some good info and ideas - and specials here:
http://www.cheapovegas.com/index.php (hope that's ok, Jack)
Box is right, the Cirque de Soleil shows are awesome. I have seen three different ones and all three were amazing. A little pricy, but nothing else compares. The other must see in my book is the fountain/water show on the strip in front of The Bellagio. They have 5 different shows or something like that, going every half hour or so. Really cool, day or especially night.
The wife and I did a ton of things there off the beaten track. The knights on horses jousting dinner show (forget the name) at The Excaliber was kind of unique. The Ceasars Palace dinner/magic show was kind of fun - about $35 I think. Pretty good food and fun. There is a Star Trek museum at the Hilton I think (off the strip a little) that was kind of fun - if either of you are fans. Catch the pirate battle in front of Treasure Island, that's free and well-done. The Volcano in front of the Mirage is pretty neat, I hear. They couldn't do it when we were there, do to weather. That's free, too.
Probably worth a cab ride down the Fremont Street downtown. There is a lights show above the street every so often that is pretty amazing - also free.
Of course, other destinations around Vegas like helicopter rides and Hoover Dam - well worth it, I hear - never done either myself.
If you don't like drunken kids, probably avoid Bally's and Hard Rock.
That should be enough for now. Have a great time - a lot to do in Vegas other than gamble.