My wife and I just booked our wedding lunch at Four Seasons for next year and we were quite impressed by the hotel and their sales service. We were deciding between Mandarin Oriental and Four Seasons, and decided on Four Seasons because my wife really loves the ballroom. It has really nice tall windows, and the natural lighting is really awesome during lunch. Really cliched, but when we walked in to the ballroom, we both went "this is the one" (and at this point, we had pretty much seen all the major 5 star hotel ballrooms).
Oh, if you are interested in FS, be sure to ask about their AMEX* promotion - we got 20 extra bottles of wine for free, and given people don't drink much during lunch, I think that's definitely more than enough. I was quite surprised by how generous they were, given that FS has a reputation for being really stingy with perks.
*note: you need a real Amex card, not a bank AMEX card, though it shouldn't take more than 3-4 days to apply for one