Welcome to flyertalk Susie, you're going to have a fun time in Vegas. Many things to see and do. Hotels are cheaper on Sunday through Thursday nights though during a convention week it will get expensive. If rates are high for a particular week, check another week's rates. As grizzly stated, MGM is a nice hotel especially for folks who do not go very often. Restaurants at the MGM are awesome. MGM is towards the south end of Las Vegas Blvd. A little further north is Monte Carlo, also a recommended hotel (IMO) and within walking distance to Bellagio, etc. Check out the O show at Bellagio.
http://www.bellagio.com/pages/frameset_noflash.asp

MGM hotel: http://www.mgmgrand.com/pages/index_flash.asp
Monte Carlo hotel: http://www.montecarlo.com/

Here is a link for coupon sites that you might find handy:
http://www.flyertalk.com/forum/showthread.php?t=452366

Lastly, all the major airlines fly to Vegas from Orlando. Non-stop flights are on Song, America West and Southwest, however, generally only one non-stop flight a day.

One more tidbit, sign up for a Players Card where ever you feel like playing, you just never know where you can get some comps