This is a great discussion. I had considered moving to Northwest in 2000, from Delta Platinum. However my last couple trips on Delta have seen much improved customer service both on the ground and in the air. So I think I will keep Delta first and continue United as a back up.
Hotels are a different story. I am out about 180 nights per year. I have split my stays to reach Gold level on Hilton, Platinum on Hyatt, Platinum on Starwood, and Black on Marriott. This year I am moving it to Marriott , Starwood, Hilton and then Hyatt. I will still look for special offers that could change my mind, but I am going to focus on getting top levels as quickly as possible.
Hilton has done everything they can to discourage my business.
Here's to a great year of travel. Lots of Bonus offers and more time to travel for leisure(yeah right).