Three route options:
7 miles, but it involves crappy road conditions and is boring.
13 miles, dedicated bike lane and decent roads otherwise; bad wind option on the last 3 miles. It turns into a constant Gulf offshore that is S/SE 15-25 daily here.
21 mile route, has the same wind option but it's the most fun. I generally do this at least 4 days a week, both directions.

I found a 32 mile route, and tried it once. It was hell working all day without a shower after 32 miles.