I would like to see hotels and rental cars combined into a possible 12 hits. That gives people more flexibility. Some people can't rent cars because of age, disability, etc. But they may stay more in hotels. So make it 12 max hits of hotels and/or rental cars. If you can get all 12 hits from hotels, then those who can't rent a car through no fault of their own are not punished and don't start the Grand Slam at a net -6 disadvantage for possible hits.
If this isn't doable, have maybe 6 possible hits from the shopping mall with 6 different merchants. You can keep the $1 hits down by saying minimum $10 or something.
Having a better scoring system in real time online would also be huge. The old Northwest promotions had great accounting throughout the promo. There's no reason US could not do the same.
I also like the hit for flying US Airways and why not one for using US Airways Vacations? They do have some great Vegas deals.