I think a folder would work great for uses you describe. Just be careful of the fit. I had a Dahon Boardwalk and while I could ride it is felt very cramped for someone my size (6'2"). The seatpost was fully extended and the handlebars were much to close. However you are smaller and the newer models claim to fit larger riders better so you may have no problem. If a Dahon doesn't work I'm sure BikeFriday could accomdate you.
Craig