As you have 160 nights, I would definitely stick to at least two programs. I heartily agree Hhonors Diamond is much more valuable to acheive than Starwood Platinum. The waiver of blackout dates for Diamond members is the invaluable compared to being a Gold member.

Starwood has a higher quality of hotels, but I don't agree that the points are more valuable. They accumulate slowly and redemption levels are high for their premium properties. On Hilton I can go anywhere in the world for week for 150K (or 100K for Hawaii). Given a 5 to 1 conversion rate between the two programs, I should be able to stay anywhere for 30K points for a week at Starwood. You won't find many hotels where this is possible.

Starwood does have been customer service and generally higher quality hotels, but they also nickel and dime you to death, which lessens the experience for me. ($2 for a toll free call, $4.95 for a bottle of water).

If you can stay anywhere, you might try Hyatt. They are my favorite program, but unfortunately are too pricey for me and a bit sparse on properties. They also have a great Diamond amenity. On my honeymoon I want to the Grand Hyatt in Bali on a Gold Passport stay. They treated myself and my wife like royalty in a magnificent suite overlooking the ocean. Because of their lack of locations they wouldn't be my primary, but they'd be a great secondary program.

Cheers!