I value SPG Gold at whatever the 250 welcome bonus is, + the 1 extra point per stay.

So....very little. The only upgrade I've ever received was at a virtually empty hotel in Egypt, and that was from a garden view room to a Nile view room.

Granted I have it as a benefit of my Amex Platinum card, so you can take my opinion with a grain of salt, but I find Hilton Gold to be a more worthwhile mid-tier status to hold. Also, IMO, the difference in benefits between Hilton Gold and Diamond is much smaller than SPG Gold and Platinum.