The wife picked up a very old paperback of day trips around Texas. I'm willing to bet they still print something of the likes of it.
Not knowing what you have seen makes me reluctant to start naming off stuff.
i have an AWD suv so rough roads do not bother me.what is your mode of transportation? Car, truck, or motorcycle? Do you like nice sweeping curves on back roads, scenic routes, or prefer to get there quick on the freeway?
Make sure your drive through Llano (Near Burnet and Lake Buchanan). When you get there, visit Cooper's BBQ. Among other things, have the smoked pork chop. Drive through Marble Falls, visit Pedernales state park. This is Texas! There's always something to see. If your wife likes wine, there are all sorts of wineries in the Hill Country. The Comal Dry Creek Vineyard is nice and they've got some interesting wines.