Starbucks the world over. If they might give you any trouble, stare vaguely at the menu on the way in. One can always change their mind to not order something on the way out.
Starbucks has restroom codes in large cities with homeless populations. They won't give out unless you buy something.
One of the Boulder Colorado Starbucks has a biohazard needle disposal box. Either that's for people with diabetes or there a high population of IV drug users.
