I switched to Hyatt and I've been very happy. The Diamond breakfast amenity alone is unreal- fully comped breakfast if the hotel doesn't have a lounge. When I stay at the Andaz West Hollywood in a confirmed suite on a reasonable corporate rate I get breakfast for 4 every day, which usually comes to $100+. When they bring the check and you tell them you are a Diamond, they literally take a red pen and cross out the whole amount- all you leave is tip.
Plus the highest category award nights are only 22,000 and you earn more points per stay (1,000 point Diamond amenity, lots of 2,000 point additional bonuses, lounge closure bonuses, etc). Plus, I've gotten upgraded to suites on award stays at the same rate as SPG, like to a huge suite at the Park Hyatt Buenos Aires (
trip report with pics and video).
Overall, the grass has actually been much greener for me (though I did requalify for SPG and stay when its convenient). Whether I'll requalify for SPG again in 2011 totally depends on if they have robust promotions or start doing confirmed suite upgrades. I don't miss the days of haggling for suites.