Off the top of my head -
PNC Park - Like others have said this place is top of the mark. Absolutely perfect view across the river and not a bad seat anywhere. I've been there several times. "Best" story I have, I went in college and bought my buddy who was 19ish a beer and I had some popcorn in my hands (not sure why I didn't have a beer as well). He gets stopped by a cop who asks for his ID and he completely froze. Without missing a beat I said he was carrying it for me so I could eat my popcorn. Quickest lie I've ever come up with. The cop bought it, asked for my ID and off we went.
Progressive Field - Even if it werent for the decades of memories here, this place will always been near the top. Unfortunately, the shipping container renovation was way off base and ruined what was otherwise a great update to the stadium. Im really looking forward to see how they fix that in the future.
Wrigley Field - The stadium, seats, field, etc.. aren't all that great, but yea the surrounding area and the history make it a must visit. I got the absolute worst sun burn of my life (we're talking ooze seeping out of my face bad) from sitting in the bleachers here. Would do again.
Municipal Stadium - These are my first memories of baseball. Seeing the giant Chief Wahoo sign as you walk in is a vision I'll never forget. Also I remember it was always so empty that they had an animation up on the scoreboard encouraging you to bang the two empty wooden seats next to you up and down to make noise. And bathroom smell? Yikes, the troughs in the mens room were a complete nightmare for little kid me. You would stand there waist high next to a bunch of drunk men all packed around a trough and their piss just sploshing all over you. Vile.
Old Yankee Stadium - Sorry Pip, I hated it. Only got to visit once, also in college. I sat in the upper deck. Man, the smell was awful, like burnt rubber in the entire area. The speaker system was pretty much non-existent, like did they only have one speaker located somewhere in center field? I swear I saw a rat running out from under a hole in a door in the concourse. If it werent for the history and being in NYC, this place would be the absolute bottom.
Great American Ballpark - This stadium was a pretty massive miss. With the riverfront in front of them and the downtown Cincy buildings behind them you would have thought they could have found a much better way to feature either view. As it sits, there's really nothing too memorable about this place except for the riverboat they stuck in the outfield. It feels like a discount bin knockoff of PNC.
Guaranteed Rate Field - I cant remember what it was called when I went and its not that the stadium itself was overly horrible, although the South Side of Chicago is horrifying if you stray more than a block or two away. It was just completely nondescript and had the most overly amplified sound system that would play some sort of sound effect or noise between every GD pitch. It's been posted before, but there is an absolutely amazing article that talks about just how badly they messed up the planning and building of this stadium. I'll see if I can dig it up if anyone is interested. Good baseball history in it.
Others
Fenway - I went with my family for an Indians series against the Red Sox sometime in the early 2000's, maybe spring of 2001? We were in town for two days and were staying right across the street from Fenway. The first day was nonstop rain and the game was postponed before gates were ever even opened. No worries, my brother and I went into the ticket office and exchanged our tickets for the next game. It continued to rain all through the night and never let up the next day either. Both games got cancelled and I never got further than the ticket office before we had to leave.
Thurman Munson - Nothing great at all about the home of the old Canton Akron Indians, but my memory of watching young Manny Ramirez hit a ball further than I ever imagined possible will always stick with me.
Canal Park - Really, really underrated cheap kid friendly entertainment. I took my kids their first baseball game this summer and they had a blast. All the mascots walking around, the perfect rebranding into the Duck theme, and some awesome promotions made their night. Pretty easy to catch a foul ball there as well, if youre into that kind of thing.