Been there many times, know it like the back of my hand. It's just about 45 minutes away from where we live. Like others have said, be sure to hike with plenty of water this time of year. A nalgene won't cut it. Have a Camelbak or similar hydration pack for each of you. A hat, a bandana to wet and put around your neck, some good snacks, and some comfortable hikers are priorities. Also, no sleeveless shirts or your shoulders will be cooked. Even with sunscreen.
If you are gonna be in the area for several days also check out Longhorn Caverns State park and Pedernales Falls State park as they are just down the road a little ways and are well worth exploring. The caverns are perfect during the heat of the day when you would rather not be on the HOT granite at Enchanted Rock. If you need any other info just shoot me a message and I'll give you my phone #.
And Happy Anniversary
C. Wolf