I am having a hard time deciding whether to book 6 nights w/ Costco @ Conrad BB or directly with Hilton.

Costco Price (Sept 4th - Sep 10th) 6 nights. Promotion is buy 6 pay 4 and includes breakfast and dinner and boat transfers = $4840 for a garden villa room. Pretty great deal!

Hilton cost direct is 4709.33 for same room type but no dinner included... dinner can be up to 90 per person per night. 180 x 6 = $1080

However..

- I have the American Express Aspire Card which gives me diamond status w/ Hilton and I would earn approximately 388K Hilton points (valued @ $2,289) when all said and done (Sign on bonus + Points for resort purchases) for the stay using that card. With diamond status and that card you get $250 Hilton statement credit (say you purchase food/drink/spa stuff @ resort) I found out Costco won't let me use the American Express card to book the trip through them so i would lose out on 75% of the above points. Also the conrad doesn't recognize diamond status when booked through a 3rd party. Also with diamond you get complimentary cocktails (1 per person) and Breakfast buffet is included complimentary with diamond.

Probably the biggest miss out of all is that w/ Diamond you can get suite upgrades based upon availability so we'd be missing out on potentially getting upgraded from a cheaper garden room to an overwater bungalow priced @ $1200/night...

What would you do in this situation? Book direct and hope to capture all the glorious benefits? or book costco as you may save more overall and have a possibility of still getting upgraded ?