I have stayed at both multiple times. The galleria one is nicer, but I usually stay at the downtown one, because of proximity. It is easier to walk around downtown. However if you stay at galleria downtown isn’t too far away. The galleria does have a ice skating ring. My kids always like to go to the aquarium downtown, they have rides, tigers and the food is good. There is also a nice park called discovery green downtown. Minute Maid park is always fun too, they used to have day tours on days they didn’t have games. I haven’t looked into it in a couple years so not sure if they still do.
As far as getting an upgrade I rarely get upgraded to a suite at either one. I would probably use the suite upgrade if I were you.