Not knowing the sorts of things you like I will just list the things we have done on our various Vegas trips!
Must do's: Look in all the theamed hotels, they are amazing. Our favourites to look in are: Bellagio (you must see the dancing fountains both in the day and night time. I like to have a drink at the Fontana bar on an evening and watch them from there - see my tag and avitar pic!!), Venetian (gondola rides are nice), Palazo, Wynn (have a drink in the parasol down bar and see the night lake show), Paris (you can go up the Eiffel Tower, great view), MGM (the lions are cute!), Mandalay Bay (the shark reef is worth a visit), NYNY (great coaster if you like those things), Ceasars (amazing shopping and the fountains move and tell stories using fire and ice etc!)
Shows: Vegas has some great shows, we love Cirque shows and our favourite in Vegas is O. There are also some other great magic shows, commedians etc. The Sirens show outside TI on an evening is free to watch and a fun way to pass half an hour or so.
Food: Vegas is famous for buffets and they are great value. We like the Buffet at the Bellagio (last trip we stayed at the Bellagio and had breakfast at the buffet every day for free at it was always really good and the servers cleared away really quickly and filled your drinks quickly too), Luxor and Mirrage. Vegas also has many wonderful fine dining restaurants, I'm not sure what type of food you like but we have had a wonderful steak at the steakhouse at the Bellagio, but one of our favourite meals ever was at Nobhill at MGM, the somalier there was amazing and did great wine paring with our food.
Shopping: If you like to shop Ceasars and Planet Hollywood both have amazing malls. The Fashion show mall is great too, all these are on the strip. There are also outlet malls at each end of the strip but you need to take the trolly to get to these.
Old Vegas: If you want to see the Old Vegas then you need to go to Freemont Street. Here there are the old Vegas hotels and casinos. The 2 block area has been done up, it is under cover and there are no cars allowed down the street. At night the canopy is a giant TV screen that does verious light shows.
Things maybe to avoid: There are a few hotels on the strip that I would not go to again, Circus Circus IMHO is a dump, The Stratosphere, whilst it is good to go to the top to see the amazing view and to do the thrill rides (yes we did them!), the resort itself can be skipped. Hotels such as the Sahara, Ballys, Imperial Palace, Riviera, Monte Carlo although are OK, they are nothing special so can also be skipped if you are short of time.
If you only have 2 nights you might not have time to do this but it is worth a mention: Helicopter flight to the Grand Canyon. We have done this twice now on different packages. You fly over the Hoover dam, land in the Grand Canyon then fly back down the strip.
Thats all I can think about off the top of my head! I've been to Vegas a few times so if you want any help feel free to PM me.
Oh, just thought a thing I did last time. If you want a relatively cheap momento of your trip, collect a $1 chip from each casino you visit. I did this last time and colelcted a $1 chip from every casino on the strip, all 27 of them!