The Hyatt program is fantastic, especially if you are Diamond status. I had Diamond at Hyatt a few years ago and one of the things I especially liked was the 1-800-Check-in feature. Your call gets answered by a specialist who places you in the best upgraded room, etc.

The downside is that there are far fewer Hyatt properties than Hilton properties and affiliate properties (i.e. summerfield suites, etc.) don't count as night / stay credit. Things may have changed, and I haven't been part of that program in a few years, but that is the way I remembered it.

On a side note I have only two trips booked this month, but both of them are going to SPG. I'll still give HH some stays this year and will make Diamond again, though via the AMEX spend.