Oddly, I actually found it easier just me and the kiddo. One year we did a trip with her mom (my ex) and her uncle (age 10 at the time) and trying to manage the whole group was just a mess. So much so that I suggested we start splitting off into groups of two and meet every few hours.
Not an issue when it's just me and the kiddo. I have been to Disney a lot in my life (Florida Annual Passholder growing up), and so there really isn't much on my bucket list, so I let her drive the plans the first few trips. Now that she's been several times, and she's a tad older, she is easier to reason with.
That said, I did sneak in several "adult oriented activities", such as signature meals, on my trips. It was rather easy, with a little girl. We went back to the hotel, dressed up, and I made a big deal about our "fancy meal". The kiddo likes to have some soda in a wine glass at these meals so we can "toast". Never really had a problem with her accepting such activities, however the trade off are things she enjoys (and I am meh about), like character experiences, etc.
The only duty that I found rather difficult, being that I'm a single father with a daughter on the trips, is bathroom duty. When she was young enough that it was ok to bring her in the men's room, or to use a family restroom (which were godsends!), it wasn't that big a deal. But, once she hit a certain age, her joining me in the men's room, or me joining her in a family restroom, really wasn't appropriate any longer. Waiting for her to "finish" was always a quandry, and our 2012 trips I have some rather interesting stories.
1) At EPCOT she went to the restroom over in World Showcase. The one that's right next to the small snack stand, just to the right as you enter World Showcase. I told her that I was going to get us a soda to share (it was hot) while she went, and pointed out where I would be (it was about 15 feet away from the restroom, and I could see the entrance from the line). Well, she slipped out, I guess while I was paying for the soda, and decided, in proper kiddo fashion and authority, that rather than meet up with me in the line, or wait by the door like I had told her, she wanted to play with the ducks! So, she walked about 100 feet away, to where the ducks were congregated, over by the tree/smoking section, and was having a good ol' time. Me, I was FREAKING out! Granted, she was nearly 9 at the time (1 month away), and astute enough that if she was lost she'd find herself a helpful CM...but, that didn't stop my stomach from turning and a Grade A Class 1 Parent Panic attack to ensue. When I found her, I was so relieved I couldn't even be upset with her.
Same trip, but at Legoland...
2) She had to go to the bathroom while I was in line for tickets. It wasn't busy, and at Legoland they have a public restroom/locker setup within clear view of the ticketing counter. I watched her walk to the restroom, and kept an eye out. Paid for our tickets a minute or two later (it wasn't very long, but potty can't wait!) and walked over to the restroom. The incident at EPCOT had already happened at this point on the trip, so I was watching it like a hawk.
3 minutes passed. 5 minutes passed. I started to get worried, so I poked open the door just a bit and called out her name. Yep, she was still in there!
3 minutes passed. 5 minutes passed. I called again, and yep, still in there!
I asked a nice lady who was entering the restroom if she would mind checking on her for me. A few minutes later, they come out. It turns out my kiddo had gotten a new dress from a store in Mexico on the cruise we'd taken the week before, and couldn't figure out how to get it back on after doing her business, but was too embarrassed to let me know (she was determined to figure it out!). Well, she sortof did. She ended up getting her arm and head through the headhole (is there a proper dress term for this? I dunno, I don't wear dresses...), but couldn't figure out how to get herself unstuck (she was, according to the woman, stuck in there pretty darn well too!).
Yeah...those moments really worried me. But, otherwise our trips have been a blast, and now they are just funny story/memories.