we did the following:
1 whole day devoted to walking the strip and walking through every major casino (maybe not 100% but most of it).
1 day for valley of fire tour
1 day tour of the grand canyon / hoover dam
check out trip advisor/vegas forums for daytime shows (usually drink/1 hour show) for $10-$20
check out the discount ticket counter for sales... Think we got 2 tickets to blue man group fot $75... Probably can find Penne & Teller, Carrot Top, or Wayne Brady for a decent price
Other things include the Pinball Hall of Fame, Atomic Testing Museam, Madame Tuseau's (Spl?). Think there is also a cheap mafia tour and a decent murder mystery scene tour there. There is also a place you can pay to shoot fully auto weapons indoors.