Hi Seankin,
I am too looking at smaller venues for my wedding and some of the venues you mentioned above are in my list to consider too. Like what Aquaelffe said, you will be looking at the Tanglin Room for REgent hotel and it is indeed disappointing. I went to their wedding fair hoping for something decent as I quite liked the ambience of the hotel and their food but what you will be getting are a couple of meeting rooms opened up, with a long march in as it will be 9 rows of 2 tables each. And it is indeed VERY difference from their ballroom.
Goodwood Park's Tudor Ballroom requires a min. of 18 tables for weekend dinner and the reception area is rather pretty. However, the room isn't very big so staying at 18 tables would be good cos I went to have a look at the room with set up for about 20 tables and I felt it too cramped up.
You can consider Mandarin Oriental? The food's good and I hard that they do have smaller rooms. Or Fort Canning Hotel?
Do email and enquire if you can drop by for a site visit. That would definitely be helpful as everyone has different opinions and preferences.
Good luck with the venue hunt!