Definitely very lucky. Ive been to at least one game in every series the past 10-12 years or so, and random other games because my best friends are Dodger fans.
Not every game does something happen, but 75% of the time it does. Whether its involved me or not. Ive seen plenty of stuff involving other fans at non Nats/Expo games.
The biggest problems are in the cheap seats - the left field pavilion and top deck. LF doesn't serve alcohol anymore because of the problems that have happened out there. I stay out of those sections anyway, but it's really bad when you're there. Lately I have done the RF all you can eat, and because they are rather expensive seats, you don't run into a whole lot of jerks. I have seen others get into it though. Anywhere else that they serve alcohol though, things can get interesting.
I like the Angels better because I think they are a better team, have ab etter stadium, cheaper prices, easier to get to and from, and I live 5 minutes from there.