I have always found it odd that the lower-priced lines provide free broadband access and the upper-end ones charge for it. I'd prefer to see that bundled and would pay more for the room.
I don't think I'd pay for healthy snacks or toiletries (I like to choose my own and as a man, can get small sizes for carry-on). I think women might be much more positive about his. I'm not sure about a treadmill in the room. I stayed in a really nice hotel in Mexico City over the summer but worked from morning until late, went out to dinner, and never had a chance to use it.
On family trips, I am less likely to want to pay upcharges. Recently my wife and I spent a few days at the Hyatt in Kauai and I found myself a little annoyed by the continual signing -- for me luxury treatment involves not having to weigh the little things ("Is it worth $27 for a decent but not great buffet breakfast?").
But, I value your search for things that would add value for your customers.
Incidentally, I like the Starwoods/Amex card and am impressed with the Starwood/Amex OPEN small business card. I have the former and am likely to get the latter.