The Sons of Hermann dance is every Wednesday at 8PM. This dance takes place in Deep Ellum and follows a similar format to DSDS. The Intermediate "Beginner Plus" lesson is at 8PM, at the same time as the newcomer lesson (in the old bowling alley downstairs). The dance then runs through midnight. There's also a Karaoke DJ in the bar, so on their website it's called "Sing and Swing."
The only Dallas dance studio offering Lindy Hop is The Rhythm Room. Their swing dance lessons are generally held on Mondays and Wednesdays, though there can be events on other days, too. The Rhythm Room is on Lower Greenville Ave, and is an excellent way to learn Swing Dancing with dance studio style progressive classes.