For the database field labeled "Location", in the memberlist, how about splitting that into two fields. One would be "State", or "State/Province", etc., and the second would be "City".
This way, when doing a sort of member's locations, you could sort just on the state, and or the city.
Say I want to see who lives in Colorado, I would sort "State" in ascending order and scroll down to all entries with Colorado. Now, I ...