Hi Alexandra,
I'm thrilled to know you'll be visiting the
Disneyland Resort for the first time with your 4-year old!
Since
Park rules establish wagons are not allowed inside the Parks, I definitely suggest you check out a stroller rental.
The Disneyland Resort
stroller rentals are sturdy, reliable and very easy to maneuver around the Parks.
You can also Park hop from Disneyland to California Adventure with your stroller rental.
Now, if you'll be staying at one of the three Disneyland Resort Hotels or at one of the Good Neighbor Hotels near the Parks, you can also hire a third party stroller rental company, like Traveling Baby to deliver your pre-ordered stroller to your hotel room for as many days as you indicated in the reservation.
I hope this helps!
Thanks for visiting the Disney Parks Moms Panel!
Wishing you a Zip-A-Dee-Doo-Dah Day!
-Anabel M.