With how HOT & humid it has been in Anaheim this summer & this time of year tends to be some of the worst of the heat/humidity I would leave the back-pack home.
I would work to make the stroller as comfortable as possible in the heat & when she just needs a break from that, go to places that are great for little to run off the steam (Goofy’s Playground, Donald’s Boat, Mickey & Minnie’s houses & the Post Office areas of ToonTown, Tom Sawyer’s Island in Frontierland, Tarzan’s Treehouse in Adventureland, Redwood Creek Challenge Trail in DCA).
We just got back from a trip with our 16 months newish to walking baby boy (only started walking at 14 months). Even though it wasn’t his first time since he started walking, it was the first time where he could really walk around stably & he wanted to test his newfound walking confidence at DL. It was hard to manage letting him walk with crowds. But with it being hot he wasn’t such a fan of being contained in anything at all so we did manage it (we have a stroller as well as a Moby wrap & everytime we pulled out the Moby wrap he protested at the extra layer of cloth on him). So we did have to make sure that he felt comfortable when we put him in the stroller, including having a clip-on fan (that was pointed at him out of his reach so he couldn’t pull it off to play with it), snacks, cooling towel & hydration.
Also, some shows that are fun & interactive that provide more breaks from the stroller & perfect for her age are Disney Jr. Live in DCA and the Royal Theater show in Fantasy Faire. At both there are areas on the ground where kids can sit.
At Disney Jr. it is an indoor (AIR CONDITIONING BLISS) theater with the majority of seating on the ground. You can sit with your little one anywhere not in an aisle. (There are a limited number of benches at the very back & sides of the theater but the area is so big that unless my kids were near my bench, I wouldn’t sit apart from them). This show encourages them to stand-up & dance & is very fun & music filled & if you watch Disney Jr will have recognizable characters.
Fantasy Faire is a smaller venue & outdoors (but shaded). The front part of the theater has a bunch of rugs where children can sit & at the back row of rugs parents can sit with their kids. There are also several rows of bench seating so if you felt comfortable with her sitting on the ground without you, you can have a seat. The theater is really small & intimate & the kids are so well entertained with the show that I’ve never had a problem with my kids sitting apart for this show & I usually sit in the benches & they on the rugs (not the baby obviously yet, but my 2 older kids who first sat here by themselves at 2 &4). I just make sure they know exactly where I am sitting so they can find me if something unexpected happens (& for the end of the show).
One last place that came to mind is the Animation Building. The lobby area is HUGE & plays a loop of all the best songs from Disney animated movies & displays not just clips of the movies on the giant surrounding screens but also TONS of the concept art/rough sketches that lead to the final product of the movie as the music is played. It’s so beautiful & sometimes when we just need a break we go into the lobby (also air-conditioned) just to get away from the heat & let the kids dance to the music. If you’re lucky they’ll be seats available as they do have couches throughout the lobby so you can watch her & take in the sights. The line for meeting Anna & Else is also in this same lobby so if she is a Frozen Fan then you’ll want to do that for sure & the wait is always enjoyable so I don’t mind waiting up to 30 min in the lobby since the view of the animation clips is so awesome.
Anyway, I could go on for days & days, but let me know if you have other questions, want any other suggestions! But bottom line- ditch the backpack, let her explore with you nearby & make the stroller heat-comfortable for the times you just need her to be contained.