For years I subscribed to Southern Living magazine. It's great for the new homeowner below the Mason-Dixon Line. It has tips on Southern travel, gardening, and food. The most important article I ever read came in the February 2007 issue. "Stop! Don't Chop Crepe Myrtles" by Steve Bender taught me how to truly care for the gorgeous summertime trees.
Like most Southerners, I'd been taught to chop the tops off of crepe myrtles every winter to keep them at the desired height. Everyone does it: you can drive down any street in Murfreesboro these days and see the landscape companies chopping the tops off the crepe myrtles in the road medians. Whatever you do, never hire a company that does that!
If you need a shorter crepe myrtle--as the City of Murfreesboro clearly does, and as we do next to our deck steps--then buy a dwarf version such as Hopi. They top out at 8 feet. If you want something tall, as we do on the corner of the house and side of the deck, then go with the regular kind. They'll get as tall as 20 feet and provide some decent shade in the hot summer months. The only downside is that a tall ladder is necessary for your winter pruning. Preferably a tall ladder and a tall husband, as my 5'3" frame can't reach high enough to prune the tops no matter how high the ladder.
If you don't top them, what do you do? Just "clean" the main branches by pruning off all the secondary growth from the year before. You'll find the activity is instantly gratifying. Sure, there will be nothing but a bunch of dead-looking sticks coming out of your mulch, but come summer you'll have clean, healthy plants!