Fellow adult here and I would also love to meet other adults in the game to quest with. I have tried the "Pixie" realm and it is the worst. I can fight goons in there forever and never see anybody. When I do see people in that realm it is a lot of kids with no chat period. I have started using the WU realm and it's not bad.
Here's an idea, if you are an adult and want to meet other adults in the game to play with use some kind of a badge like "Peacemaker" or whatever badge you want to come up with and spread the word.
I think that there should be an age restriction, because of child preditors. It could be setup by birthdate and drivers license. Children are on sub accounts. The down side is that the parents won't be able to play with their children. But, I would rather protect the children.
I don't really think there should be a Wizard101 "adultland" (Like in Fairily Oddparents lol) because I just think that there should be all ages together. And besides they would getting away from me because I'm not even 12 years old yet :(.
AGAIN, the OP is not asking for an adult only realm. Just if there is any realm or realms where adults tend to gravitate to.
Nothing wrong with wanting to hang out with people your own age from time to time. People of ALL ages appreciate some time with those in our own age group on occasion.