I was just looking at the various rates of return on rewards credit cards, and they break down as follows. For the miles and points cards, I divided the cost of the redeemed reward (e.g. a flight from LAX to NYC) by the number of points required to redeem it. A $350 flight that costs 25,000 points to redeem is worth a 1.4% ROI (350/25,000).
1% - Discover and most cashback cards (no cashbacks over 2% except for select purchases)
1.2% - Marriott rewards Visa Card
1.5% - Airline miles cards (Northwest, United, etc)
3.5 to 5% - The Starwood Preferred American Express card
As you can see, there's really nothing close to the Starwood Amex in terms of bang for the buck. I just financed 5 nights in Europe at a nice Sheraton on points I collected from this Amex card.