Hyatt for location. Sentosa is not convenient for everyone, esp those who doesnt drive.
I think it is more wise to be able to confidently hit the min tables. Some guests last minute might not turn up. Having to pay for empty tables not only burnt a hole in your pocket, but also doesnt look good as well.
And, It doesnt mean that pple will you u more for W or hyatt given the name. Pple usually give you the amt that they can "afford" and if you cant afford / do not wish to lose so much, choose a cheaper hotel.
To be frank, if I got married like 10 years ago, I dun really pay attention to the market rate of all these hotels. All I know is a 4/5 star hotel, i dun really know the banquet price, I will only give the normal market rate, and not google the banquet rate. Not to be mean, but you sounded like you wanted pple to pay for your "memories" & "face". But why would your guests do that for you? Unless that location holds special meaning to the both of you, then it is a different story.
Be practical, save that money for better housing renovation, which you can enjoy for at least 5 years as compared to 1 night.