I stayed at the Westin Galleria Dallas in December and was also disappointed. I am platinum, and other than the amenity bonus, got nothing close to a upgrade.
The hotel faces a busy highway and windows are not insulated sufficiently to keep noise down.
The hotel seems to have generally standard sized rooms except for the corners, where the two rooms at each corner are small. When I checked in, I was given the second smallest room possible; it was also very noisy because of wind and road noise. (This was after waiting a couple of hours for a room to free up)
I went back to the desk, asked for a quieter room. This time I was given the smallest room possible.
Overall, pretty disappointing.