In Seattle there's an annual fund raiser dance for Northwest Folklife Festival. It's a marathon: 3 hours, nonstop, no teaching, 12-15 callers, several bands. We mostly do contra, but Sherry Nevins, who runs that dance, likes to add squares and waltzes in the mix. Since it's nonstop, there are some interesting transitions between the styles of music. Part of this is contra-to-waltz-to-contra. The contra after the waltz sometimes starts in waltz time and then switches to a square tune in the same dance.
To quote my husband, sometimes that transition is bone jarring. I once attempted to sing the contra calling to the waltz tune (not my idea!), and was less than successful.
At any rate, if the tune and dance are picked well, many contra dances will work in waltz time.
-Amy