I feel lucky to have seen quite a few very cool performances and I'm going to answer this question a few different ways so I can list more than 3 shows.
10/30/15
https://antsmarching.org/tour/ViewShow.php?ShowID=4586
Notable to me for many reasons: This was my 150th Dave related show, and my first time visiting Europe. I also met with my friends at DMBReleases.com in person for the first time. The venue itself is a converted distillery with a low ceiling, the acoustics are poor but they gave the show a unique 'club' like feel. In line before the show, my English friend Andy announced to the crowd that it was my 150th show. What seemed like a hundred people then swarmed us and cheered.
There are a lot of really cool Danish / Scandanavian fans and I would highly recommend seeing the band in that part of the world if you get the chance. Its a very different experience. For instance, it seemed like most people biked to the show... there must have been more than a thousand bikes parked outside.
Of musical note, the band audibled to Halloween in the encore because fans chanted for it.
9/24/11
https://antsmarching.org/tour/ViewShow.php?ShowID=4299
Dave & Jane held a moderated chat / Q & A type discussion and Dave played a solo 3 song set. While Dave played, Jane sat in the seat in front of me, enjoying the performance just like the rest of us. I was sitting so close that I could hear Dave's voice & guitar without the amplification. It was my first time seeing Dave solo, in a small theatre and I even got Dave's guitar pick after the show.
10/22/11
https://antsmarching.org
/tour/ViewShow.php?ShowID=4300
I didn't have a ticket to this show so I stood at the entrance hoping that someone walking in would have an extra. I only had to wait a few minutes and a nice lady walked up and put a ticket in my hand. It turned out to be pavilion seat, dead center, around 10-15 rows back (face value would have been a few hundred for sure). I didn't realize that until after the nice lady walked away, and only realized it when I went to find my seat.
Bridge School is a neat event but there is a lot of down time between sets, fortunately this allowed me to chat with the nice lady and her friends. They were coming and going a lot, but they were all music enthusiasts, so I felt like I was in good company. They were very curious who I was there to see and of course I was happy to respond that I was there to see Dave Matthews. After one of the sets, the nice lady and one of her friends departed briefly, leaving me with just one new friend. I asked her how she and her friend's got such great tickets and she says something to the effect of 'the woman who gave you that ticket is Livia Tortella the co-president of Warner Brothers Records, and the other guy is Bill Werde, the editor of Billboard Magazine.' At that point I'm thinking, and who the fuck are you, the Easter Bunny? No, as it turns out she was the president or co-president of Warner films. No big deal, just me and the industry big wigs enjoying a show. Long story short I made new friends that night, and Livia gave me a free 4 pack of seats for the next night's show. All tolled it was $1K+ in free tickets and a genuinely incredible experience.
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here are 3 more noteworthy top experiences.
11/5/15
https://antsmarching.org/tour/ViewShow.php?ShowID=4590
"being lost somewhere in Paris" became more than a lyric, it was a lived moment.
1/16/14
https://antsmarching.org/tour/ViewShow.php?ShowID=4457
Dave nailing the Dixie Chicken interpolation during Crash, while being in the heart of Dixieland. The way the crowd roared was pretty magical.
12/18/12
https://antsmarching.org/tour/ViewShow.php?ShowID=4384
Stefan played the Star Spangled Banner, perhaps not knowing the history of the song in Baltimore (
https://conduitstreet.mdcounties.org...es-came-to-be/. Stefan seemed surprised when the crowd erupted with "O's"
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If I'm going strictly historical/music/set based shows my top 3 are probably: 7/30/03, 9/12/04 and 1/16/04... maybe 8/7/04 too.