I went to the 3 day Star Trek convention in Birmingham just prior to the rollout of season one of Picard. Sir Patrick Stewart was in attendance, and was a speaking guest in a (paid for) hosted talk. Although I bought a three day 'Commander' package, I (naively) thought I could pay on the day to watch him on stage. The tickets for his talk sold out way before the convention started. What struck me the most was the insanely loud cheering that came from the (curtained off) stage where he was talking. The noise could be heard throughout the whole of the exhibition hall, and all of us in attendance at the convention who weren't on the other side of the curtain stood there wishing that we could join in. Undoubtedly the star of the show.
Not been for the last couple of years, but these are truly memorable events. One year I saw Sulu and Chekov together in a live talk which was pretty special, another with Captain Janeway, another with The Shat, with Deanna Troi (who was very funny) and surprisingly enjoyable Wesley Crusher, who was much more entertaining in real life than the character he portrayed in TNG.
The conventions are also really cool places to go. Not only do you get the chance to chat and get photos with the actors (I had a photo taken with Bill Shatner) and get to see some cool props, as well as the bridges of the Enterprise and a Bird of Prey, but the people there are really cool. From the actors, to the vendors to the other people in attendance. Lots of costumes, lots of cool geeky t-shirts and everyone so friendly and happy to be there.