Like most of the posters, my go-to card is the AMEX SPG. But since I have a load of SPG points (>250,000) and since there are some places that don't accept AMEX, I've been using the Merrill + Visa card. Once I hit $50,000 for the year (about 6 months), I'll have those 50,000 points and, in addition, get 4 nights at any Ritz Carlton. That alone is worth over 3 cents per dollar spent, and I will STILL have the poiints.

I'm still an SPG man (Centurion too), but there are lots of options out there. We do what works for us.