Natchez are a tall variety of white crepe myrtles. If you want variety, you can check out the list at Crepe Myrtle Trails of McKinney. They have an upcoming sale that you should check out.
http://www.crapemyrtletrails.org/For a friend's house on a corner lot, she had a narrow strip of parkway, and I planted 4 tall variety crepe myrtles spaced at 15' on center. I wanted 4 different colors, so I chose:
Natchez: White
Tuscarora: Pink
Muskogee: Lavender
Red Rocket: Red
If I had room for 5 (and I probably did), I should've also gone with Twilight (tall purple). Anyway, good luck, but be aware that crepe myrtles are not evergreen. There's really not a reliable "quick" evergreen option. But if you wanted to try something, the Teddy Bear Magnolia is a compact, narrow Magnolia variety that is more attractive than the Little Gem, but is smaller than the true Southern. It'd be perfect for this situation, if you had the time to wait on them, although you can find 6-8' plants commercially at Calloways.
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