Want to save on the price of a rental on your next family trip? You might try out this micro bike from Dahon, the Sweet Pea. This one is designed more for women and children. It's a bit small for us guys and I don't know that we'd really want to be seen riding around on something colored mint green or hot pink. (The company does make adult sized bikes in different colors.)
The Sweet Pea folds in seconds and is small enough to fit in the back of almost any airplane. Available for $279 from airportshoppe.com.