My first "ever" flight on Delta, I can't remember (we flew AA a lot when I was a kid, but I think Delta was in there a time or two). My first business flight ever was on Delta in 98. MEM - DFW via ATL. I remember Delta was playing with the little snack bag carts at the time and I grabbed one while boarding. I actually still have the bottle of water that came in the snack on my desk.
The thing I can remember about it is the audio. The return flight from DFW-ATL had headphones available for everyone and I ended up listening to the comedy channel. Two pieces I can remember, one of which took years for me to figure out what it was. PDQ Bach's Beethoven's 5th as called by sportscasters (from "New Horizons in Music Appreciation"), the one that took me years to figure out; and Shatner's version of Lucy in the Sky With Diamonds. I had never heard it before and had to fight to keep from laughing out loud.