Oh, also forgot to mention that you should also check out a couple blogs. Specifically look at Gary Leff's "View from the Wing" I did a quick search of "SPG Amex" and came up with these posts: http://boardingarea.com/blogs/viewfromthewing/

He also in other posts lays out his impressions of other cards.

Also, I think Frugual Travel Guy is into a credit cards. He does a lot of churning but I seem to recall reading a review of the SPG Amex there as well.