Still listen to a lot of old Blue Devils, Madison, Capitol Freelancers, Garfield(aging myself here), etc. Great stuff. Not so much into today's DCI though. Too "theatrical" for me. But still admire their abilities and talents.
Remember 27th Lancers and what about the Bridgemen? Or Santa clara's famous bottle dance? I've watched it now and then today (PBS usually runs the DCI show), but, it's lost it's military style and is now all dance and showbiz. I go back to the 70's.
Never marched in one, but found the DCI contest on PBS in 1976 or 1977 and have been watching it ever since. One of my science nerd friends was drum major of the marching band in High School and spent the summer after he graduated with a DC up around Chicago. He had some very interesting stories to tell after that summer.