If you're from out of state and you want a feel for the idea of "Texas," then this is the place to go. You can get good food, see tons of live music and even buy a new piece of western wear.
For something closer to the hotels and wedding venue, Grapevine offers a great downtown area with lots of walkable shops and restaurants. We highly recommend Harvest Hall, a food court attached to the Hotel Vin.
Whether or not the Cowboys have a home game, AT&T Stadium is an awesome place to check out if you're a sports fan. They offer tours year-round and it's also next door to the new Rangers ballpark.
Great for shopping, food and movies if you have a couple of free hours but don't want to venture too far from the Grapevine area.
One of Dallas' main tourist attractions, the Sixth Floor Museum offers a history of President Kennedy's trip to Dallas in 1963.