Additional art stuff includes:

In Dallas, the Crow Collection of Asian Art. Small, free, located inbetween the Dallas Museum of Art and the Nasher.

Also, NorthPark Center. A large mall that was built by Raymond Nasher so it has a lot of sculpture from the Nasher's personal collection spread throughout it.

In Fort Worth, you have the Kimbell Art Museum and the Modern Art Museum of Fort Worth. Both well known, both for their art and the buildings. The Kimbell will be inbetween major exhibits, but the permanent stuff they will have out will be open and free. You will have just missed the Kara Walker at the Modern. Pity.

But it really is a day trip to go to Ft Worth and back from Dallas (about an hour each way), so you may not have enough time.

And there are many more smaller museums and galleries in both cities.

You might want to check out GuideLive for additional things happening around Dallas. http://www.guidelive.com/

BillJ