I've utilized the Signature Hotels twice in the last 30 days..

Waldorf Astoria (Orlando).. Went to Disney for the Christmas event, stayed there since it was on property but not crazy resort price.. Got everything listed on the Signature site, including getting upgraded to a Disney view room for free, which was great for the kids..

Aria Sky Suites (Vegas).. I couldn't get upgraded because I had already got the 1 bedroom panoramic view penthouse suite.. So the only upgrade available there would of been to a villa which is several thousand more.. IIRC, I got a $40 breakfast credit per day and a $25 food credit per day..

Both experiences I was treated very well.. However, both hotels are fairly upscale so I'm sure I was treated the same as anyone.. They each mentioned the fact that I booked through Signature Hotels, so they were aware of the program..