I second the Guadalupe. Put it around the town of Gruene, just north of New Braunfels. Your wife will love the town. Hit the Gristmill for a great meal. Have fun!
100% this! Gruene, Tx has the oldest dance hall in the state. They always have good bands playing and the atmosphere is great. There are little shops in and around Gruene that your wife will love. The Gristmill is on my list of top 10 favorite restaurants of all time. The food is incredible, and with the weather down here right now, it's perfect.
The Guadalupe is good for bluegill, Rio Grande cichlid's, bass, rainbow trout, etc..