Some of the following suggestions may not be within your budget but I thought it'd be better to just list down as many places that I can think of for your consideration
- Raffles Hotel
- Fullerton Hotel
- Goodwood Park Hotel (min. 18 tables for dinner)
- Regent Hotel
- Mandarin Oriental
- Pan Pacific Orchard (think their max. is 12-13 tables?)
- Carlton Hotel
- Hotel Intercontinental
that's all that I can think of at the moment. you can also try restaurants if you want. There are some that are getting very popular with weddings such as The Grand Shanghai.
Good luck with the search!