I was just out near there last weekend, going to a couple wineries. There are a few vineyards on your way, check out the website:
http://www.wayoutwineries.org/Unlike the wineries right outside Fredericksburg, the tastings at a few of these are still free.
The ones in Meridian, Lampasas, and Bend are right on your way. I was at Alamosa Winery in Bend, and took Hwy 501 over to Cherokee on Hwy 16, which then goes south to Fredburg. No water crossing problems, and a beautiful drive.
If you're not into wine, keep going down Hwy 281 thru Lampasas, past Burnet, and turn on Park Rd. 4 over to Longhorn Caverns and Inks Lake.
Go to Enchanted Rock on a weekday.
In Fredburg, look for The Fredericksburg Herb Farm. The have wonderful flower and herb gardens, a pond with trails, a small restaurant, and no crowds like Wildseed Farms.