I've seen a bunch of the big rock acts, but if we're trying to pinpoint a single concert I'd have to give the nod to Ozzfest '99, when I saw the original lineup of Black Sabbath. That's an experience I never thought I'd get to have.
If we're talking most memorable shows, though, I find that those are often the ones that take place at smaller venues. I've seen my favorite band, Clutch, more times than I've kept track of, almost always at small venues with an occasional festival appearance tossed in. A more recent show that has really stuck with me (maybe because it happened not long before COVID shut down live music) was The Claypool Lennon Delirium at the House of Blues in Anaheim, where I stood like 10 feet away from Les Claypool and just watched all the crazy stuff he does with his hands.
Quoted from RoachApproach:But I think my most memorable concert experience was the Progressive Nation 2008 tour at The National in RVA.
The National is my favorite venue! I've seen some surprisingly big acts there (Rob Zombie, Jane's Addiction). Packing the crowds that those bands attract into that place lends a whole new meaning to the word "intimate." 
