I know people might think I'm crazy but Nashville can be really nice and fun. We stayed in a Hilton suites in Brentwood (absolutely huge and fabulous, room had a sep. bedroom) with a pool. Brentwood is a very upscale part of town (suburb of Nash.) and seemed very safe. Normally we would not pay Hilton prices but we used Priceline and got the room for $65 a night. From Brentwood, you can hit the zoo (very cool - stand eye to eye with a giraffe). There is a pancake place (PFunky Griddle) where you can make your own pancakes at your table. There's Grand Ole Opry - all kinds of stuff. Parents Magazine ran an article on fun things to do in Nashville. As to safety, play it smart - stay out of bad neighborhoods, get in before dark, and choose an interior hotel that's nice and in a good neighborhood. You'll be fine.
A couple other ideas - go north? Have you checked into dude ranches or winter sport places? Kids love the animals on the ranchs.
We're going north this year b/c my daughter wants to make a snowman, throw snowballs, sled, hot chocolate - the whole deal. You don't have to ski - just hang out in the snow, sled, snow tube, etc. I'm sure there's somewhere within a couple days drive. Might be a fun change and might not be as crazy as the beach during Spring Break. Mostly it's families and some college kids, but the wild kids tend to go out to some of the flashier resorts in Colorado, it seems.
Look for a family place that provides activities - you might even find one that has a kids program where you can drop DD for an hour and get a massage or something! Anyway, there are all kinds of article on the internet - just google family winter vacation and other phrases like that. Might be a fun way to get quality time!
Good luck and have fun!
Found what might be some good links for you:
Midwest Vacation Spots: 1001 Vacation Ideas
Midwest US Vacation Ideas - Family Vacations.
Winter Vacations - ideas by region
Winter Vacations - ideas by region; find winter vacations in the northeast, ... See also some ideas that cross many regions: Family Adventures are ...
JUst google - there were tons of sites from winter stuff to good deals on beach vacations!