for me brand generally doesn't matter -- except that far too many Hamptons are dumps so I don't stay at them.

Instead I offer why I like diamond. ;-)

#1 Much Better Award Availability
#2 25% More bonus points

#3 Same as gold -- free breakfast

I'd rather stay at most Hilton Garden Inn's & Homewood Suites & Embassy suites because you generally get a FULL FREE BREAKFAST. Most US hiltons give you a crummy to very crummy breakfast in the exec lounge!! I don't find the exec lounge to be much of a perk at all. But a decent free breakfast saves my per diem for spending on on dinner.

#4 Same as gold -- free access to health clubs

Free access to health clubs is nice at the few properties that have one is also a nice perk.

#5 diamond line -- I rarely need to use it so I don't value it as much as others do

#6 Improved odds of upgrades - Diamond is required at certain properties to get exec lounge access (e.g. cavalieri)