oh, mercury room is the one with pretty low ceiling i think? I can't really remember if we had it in gallery room. it's kind of like horizontal layout?
My HTB and I also had this dilemma, until recently we signed with Traders Hotel
Although the package for Riverfront is very attractive, I was a little disgusted with the people at the swimming pool. I witnessed a couple holding their solemnization by the poolside, with the hotel guests in their swimming attire witnessing the whole ceremony at their bench while sun(or moon) tanning. Ballroom has very low ceiling as well.
Traders' Gallery Ballroom looks more elegant, especially with the mirrored pillars (since both ballrooms have pillars, it is worth comparing). Furthermore, the tables can be arranged such that the tables will not be blocked by the pillars. A pity that the reception area at Gallery ballroom is pretty small, so I am intending to display all the wedding photos in the ballroom instead.