Do you like art? During one of my long layovers, I took a very enjoyable trip over to the Dallas Museum of Art. Just jumped on the Orange line DART from DFW to St. Paul station.

The museum is free and has ample wifi. (If I recall, I stopped by the front desk to sign-up for their DMA Friends program, which is their way of making the museum experience a bit more fun and interactive: https://www.dma.org/visit/dma-friends)