My mom always does a sweet and sour dressing-thing with beets - she calls is Harvard beets. But I can't remember if she boils them, or how she cooks them first.
How did you roast them when you made them last time? Whole? Cut up?
My kids scarf up roasted beets, but I have to peel and cut them up, toss with olive oil, salt and pepper and roast until they're caramelized and crispy on the edges, like oven roasted potatoes. It takes a while.
Ina Garten's recipe is pretty good.
You should TOTALLY watch the Beets episode of Good Eats with your kids.
Alton's
Glazed Baby Beets are tasty, too. They've got the sweet and sour thing going on.