I've had non-ideal experiences with this.
Last week at the W Barcelona, they asked me if as a SPG Gold I'd like Internet, Points or Drink. I said I'd like Internet and points. They said I had to choose. I said "but I booked on spg.com". They went to find a manager, who came out and said I could have both.
Just now I checked into the ITC Gardenia in Bangalore, and was given a welcome letter saying I could have Standard Internet, Points or Drink, and Premium Internet would be chargeable. I said "but I booked on spg.com" and they said it didn't change anything. Got online, pulled up the page, showed them it, got the manager out, he apologised and said that with the changes I could have both the points and premium internet.
(Didn't get to test it at my other starwood hotel since the 2nd of Feb, as my room rate there came with premium internet anyway)
Maybe I've been unlucky, but it seems hotels are at best needing to train their staff better on it, or at worst are cynically only offering it to people who both ask and push