Hi mskay!
Rose of Sharon is a great shrub/tree. It is deciduous, looses leaves in the fall. It is really a bush but can be pruned into a tree shape if so desired. I've seen them make a beautiful privacy hedge but mine are not at that point yet. They have big hibiscus-like flowers. They tolerate heat well and can be planted in full sun or part shade. They can grow as high as 8 to 12 feet and, according to this book I have here, 6 to 8 feet wide! Mine are not that wide but mine are only about 4-5 years old. They flower on new wood grown the same year so pruning shrub back hard in late winter or early spring will result in lots of beautiful flowers. (That time frame is according to book, I haven't pruned mine back yet this season but will). This first year, make sure they receive LOTS of water, especially during the summer. The flowers bloom in the summer time when everything else is fried. It's a great plant. Your in-laws are very kind to have gotten these for you and to have planted them too. Enjoy!