This might sound cheesy, but what about "I Know You" from Sleeping Beauty -- that's a waltz! And I love that song. You could throw in a few of those old classics for sure, they're so sweet and charming. Check out some old classic love songs maybe online or in piano music books. Ask your mother, aunts, grandmothers, great aunts, for song ideas -- that'd even be awesome to get a fave song from each to contribute to your list to make it meaningful to everyone there.