Hello Jennifer,
You and your Princesses must be counting down days until your first trip to Disney! And we all know that royalty must have a carriage to transport them around the Magic Kingdom and beyond. So in my opinion, it's absolutely alright to rent a stroller for older children.
I rented a stroller for my then six-year-old daughter one day because I knew my family would not be able to take a much needed mid-day break. Instead of hearing her whine about achy feet, she quietly sat as we maneuvered between attractions.
I have never had a problem leaving my stroller outside. There are often times a Cast Member is stationed at stroller/wheelchair parking. But I would suggest bringing your purse and other valuables with you.
Also, in a sea of strollers, it's sometimes hard to remember which one is yours. Even with your name tag, it's easy to starting walking away with the wrong one! So bring a long piece of ribbon to attach to the handle bar. Or purchase a balloon at the theme park so your stroller will be easy to spot!
For more on stroller rental at Disney, click
here.
Hope this helps!