FYI, I went to many hotels' wedding venues and found that there are a few good ones in mind that I can intro you based on your limitations. Note: They are not in ranking or any priorities.
They are:
1. Grand Park City Hall (Grand Ballroom - accommodate max. 28 tables, with high ceiling)
2. Concorde Hotel Singapore (Grand Ballroom - accommomdate max. 45 to 50 tables, with ceiling)
3. Carlton Hotel (Grand Ballroom - accommodate max. 45 tables, with high ceiling)
4. Sheraton Towers (Grand Ballroom - accommodate max. 40 to 45 tables, with high ceiling)
5. Waterfrond Grand Copthorne (Grand Ballroom - accommodate max. 50 tables, with high ceiling, with Waterfall/Garden as a backdrop)
6. Orchard Hotel (Grand Ballroom - accommodate max. 100 tables, with high ceiling)
7. Pan Pacific Singapore (Grand Ballroom - accommodate max. 55 tables, with high ceiling)
8. Fullerton Singapore (Grand Ballroom - accommodate max. 60 tables, with high ceiling)
9. Marina Bay Sands (Grand Ballroom - accommodate max. 600 tables)
10. Swissotel Merchant Court (Grand Ballroom - accommodate max. 50 tables, with high ceiling)
11. Furama Riverfront (Grand Ballroom - accommodate max. 55 tables, with high ceiling)
Hope this helps. Thanks!