I go as a solo adult - or with friends or family - and definitely do character meets!!
Some favorite interactions over the years:
1 - Cape May Cafe breakfast over Christmas 2010 (the Northeast Blizzard). We were at one of the tables that the seating was booth on one side and chairs on the other. My sister and I were on the booth side, and Goofy decided we needed to be thisclose to each other and literally sat down and squished me into her. If he looked over and we were separated, he would come right over and repeat the process. The kid at the table near us thought it was hysterical. (And yes, that friend communicated it to the next friend so that it continued for our entire meal.)
2 - 'Ohana breakfast the day after my first marathon. My dad is not the biggest fan of Stitch, but he humored us and played along. We were late enough the characters made a few rounds. The last one, Stitch picked up the carafe that had held my dad’s coffee (it was empty and Stitch did shake it a bit to make sure before continuing) and tried to drink it. Finding it empty, he looked at all of us and my dad said “It was me Stitch. I drank it all.” and Stitch stomped and did a “Talk to the hand!” signal.
3 - Solo trip, meeting Dug and Russel in Animal Kingdom. I had gotten a popcorn bucket earlier. The handler who was taking things from people and taking personal camera/phone pics took the bucket to set it down and Dug came over to try and get it. Got a lot of cute pics of that.
4 - Solo trip (and also with a friend) meeting Chip and Dale on the trail around Dinosaur. More than once we’ve ended up having a dance party to the music that’s playing.
5 - ANY interactions with Captain Jack Sparrow on Disney Cruise Line are amazing!!