I used to go to Otakon in Baltimore, MD every year from about 2003-2011/12. I'm not really a convention person because I get panic attacks in crowded spaces, but it was a tradition for my husband and he wanted to share it with me. The first year was really difficult for me, but I learned a lot of techniques to help me cope better in the future. Plus, my husband was super helpful and willing to walk away from lines or whatever if I needed to just get out immediately.
Other than dealing with crowds, I thought the convention itself was a lot of fun. My favorite part was the costumes. I've always loved costumes and it was fun to recognize the characters and take pictures of them. I even started cosplaying myself after a few years.
The merchandise was also really cool. I got to buy things that I could never find where I live and would cost a fortune to ship from Japan. I also liked the artroom where amateurs displayed their work. I even bought a few figures and art prints from them because some were seriously that good.
In the evenings, they had a masquerade where attendees performed skits or participated in costume contests. That was always fun and we never missed one of those events. We still love to remember some of the random things that happened during the masquerade, like when this one pretty girl came out on stage in a perfect Ciel Phantomhive cosplay and a guy from the crowd shouted, "I'd go straight for you!"
There are also concerts, Anime Music Video contests, and artist/voice actor signing sessions, plus panels for all sorts of things that anime fans might be interested in. I guess it depends on what you like and what anime convention you go to, but you can always check out the website on the con to see what they have planned and who will be there as guests to figure out if you want to go.
We stopped going mainly due to financial reasons and now life has kind of gotten in the way of us going back, but sometimes we still miss it.