Wee Wei,
I think the unhappiness was due to the constant change in the banquet sales staff at GWP this year. Not sure if they finally managed to fix this problem or not. My experience with GWP was a good one. This was before Jeanie Tan left. She was our coordinator and she was a very good one too! We like the food served. Were given a small, but very cosy and well-appointed suite. No problems with the service of the GWP staff. LOVE the ambience GWP exudes! Cosy, quaint, timeless, and very elegant. No other hotel in Singapore has the unique ambience that GWP has! It's certainly very different. I'm biased, of course! You have to be your own judge!
The Hyatt and Hilton hotels are larger hotels. Much more so than GWP will ever be. Ambience at these hotels differ greatly from that of GWP. Honestly, it's best that you go and check these places out with your fiance. You'll know exactly what I mean once you visit them! Think the Hyatt and Hilton have more function rooms and ballrooms for you to choose from. GWP only has the Tudor and Windsor Ballrooms. These 3 hotels are hotspots for wedding celebrations! Good Luck!