Basically being a high level elite in any of the hotel programs makes the program incredibly more valuable than to the general member. Hilton, Hyatt, Intercontinental, Marriott, and Starwood are the big 5.

My hotel stays greatly improved with Hilton Diamond status and Starwood Platinum. The great advantage of Hilton is the ability to exchange large numbers of airline miles for HHonors points, although the partner list was drastically cut with the deletion of United and Continental (and for me GlobalPass)in 2003. When American Airline miles can be accrued at 1 cent/mile (if you plan flights strategically for this purpose)then $750 (75,000 miles) in airline miles can be exchanged for 150,000 points and a GLON2 for 6 free nights. Of course it was better when it was 100,000 points for a GLON, but most of my GLON redemptions have been worth $1,500-2,000 for my 6 night stay.

Starwood has the edge on low category properties, especially for a platinum. I needed a room a couple of weeks ago at last minute at SFO on a Friday night. It sure is nice redeeming 2,000 points for a CAT 1 Sheraton and getting 500 points back as a platinum amenity (1,500 Starpoints net for 1 night). Considering the lowest available Hilton would have been 20,000 points I saved quite a bit with Starwood. Starwood is expensive in the high end properties. Unless you have expensive lodging folios or a good charge record with a Starwood AMEX, it is difficult to accumulate 80,000-100,000 Starpoints for a Cat6 5-night stay. At 2 cents/$1 for a regular member or 3 cents/$1 for elite that is more than $30,000 in folio charges for the award. Again, I can fly an airline and get 175,000 points with a Hilton exchange for less than $1,000 and get a 6 night GLONP2 award for a Hilton premium property.

Intercontinental has the advantage of being able to earn points at cheap Holiday Inns all over. The awards for Crowne Plaza and Intercontinental properties are relatively cheap compared to other programs' top properties.

Hyatt has the great Stay2,1 free offer regularly, but there are a limited number of locations with Hyatts compared to other program properties.

Marriott - I don't really see the appeal to this program. They require more nights than any other program to get high status and from what I read on FT upgrades aren't as frequent as with Hilton and Starwood.
It seems a person could get elite status with both Starwood and Hilton for the number of nights it takes with Marriott. I see Marriott as valuable for extended stays and they do have some nice awards, particularly at high point levels.

My strategy is generally to pay for many 1-night stays and earn status based on that, so Marriott doesn't work for me.

I am quite happy with Starwood and Hilton. I would like to add Intercontinental if my travel increases, and since Monterey has two Hyatts I need to take better advantage of the Hyatt promos so I can try some of their lovely properties I see when I travel.