sheraton is with RCI and II.
the hotels that the marriott trades too are marriott hotels not connected with II.
I think the sheraton can trade to it line of hotels.
now if you are talking about the getaway weeks that II - offers - both will do.
but I would get a much cheaper timeshare that trades with II - just make sure that the maintence fees are pretty low too - with II anything under $700 is low. (i have one with maintence fees under $500 but those are rare)