I usually go to WDW with either my husband, my mom, or both. And sometimes other family members (adults or teens) are with us. My favorite times, though, are when I'm with either mom or DH and with my adult DIS/Disney internet site friends (many of whom have kids back at home or grown kids) from around the country every December

. You should hear us all singing along on Pirates and Splash, or all shouting in unison "Tommies" on Kilimanjaro Safaris, or cheering for our guide as he/she returns in the Great Movie Ride
I have had my picture taken with characters, and I like to ride a lot of the rides in Fantasyland. I especially enjoyed Fantasyland at
Disneyland a few months ago, and I rode many of those rides multiple times when I was in the park alone (DH was at a conference). I loved that Alice in Wonderland ride!
About the only things I don't often do that are aimed at kids are Toon Town, Playhouse Disney, and character meals (I would rather eat and not try to interact with the fur characters while I do so).
From personal experience, and from watching other people in the parks and reading things on the DIS, it seems to me that WDW is often more fun for adults than for kids, even for the majority of adults who take kids (unless they have kids or a spouse who are making them horribly miserable by whining and complaining.) I think there are many parents here who would agree with me, although not all.
I can tell from the joy parents get out of sharing their experiences and photos of their children that many parents experience just as much or even more pleasure than their kids feel simply from watching their kids take it all in and play in the parks. The fact that there are thousands upon thousands of adults (primarily) who are part of the DIS and so many other sites says that adults probably love it for some reason or other at least as much as kids

. Sometimes I'm kind of sad that I don't have kids because I will never get to take my kids there and feel that joy that parents feel. But I do get to go with my mom (KayTX) and see the joy (and happy tears!) on her face

.