Calling Fairfield equivalent to Hampton Inn is a slur on Hampton.
Hampton Inn - and escpecially Doubletree - has too much variation to be pegged cleanly.
Hilton does a decent job on its own describing its brands, found here as a start. IMHO it's more useful to the OP than describing to cast Marriott equivalents.
http://hhonors1.hilton.com/en_US/hh/about/brands.do