I am have a road trip coming up, from Corpus Christi through San Antonio, Austin, Waco up to Fort Worth. Was hoping someone might have experience with some good nurseries along this route.  Any ideas would be greatly appreciated.

Fanick's Nursery is on the east side of San Antonio.

Bloomer's Nursery is a bit out of your way in Elgin.  You could take 290 from 35 to 95N in Elgin.  Then head straight up 95N which will spit you out on 35N in Temple.

Round Rock Gardens is less than a mile west of 35 on Highway 79.  If you do not go to Bloomer's, this will be on your way.  If you do go to Bloomer's, take 79 west off of 95N in Taylor (about 25 miles north of Elgin).  When you pass 35 it will be on the left side.

McEntire's Nursery is in Georgetown about a mile off of 35 at the Leander Road exit (#260 if I remember correctly)