My family is not in love with eggplant (or zucchini) - what other veggies would work instead?

Cabbage would be delicious! Its mild sweetness when braised works really well with braised tomatoes. I'm inspired now to try this. ;o)

I see from the comments, too, that someone actually did use cabbage and potatoes, adding the potatoes toward the end of the cooking time. They reported that it was wonderful! ;o)