I have 2 boys (now 7 and 4) and have been on numerous trips with them to the World. My general thoughts on strollers are that
a) they are for babies and toddlers - not for pre-school aged kids who can walk;
b) cumbersome to deal with in the parks - going light is the best option;
c) they should not be used to push the limits of what your child can do in any given day at the parks.
When we take our boys, we can sense when they're getting tired/cranky. At that point, it's time for a break. Either a slow ride, sitting down for a meal, or heading back to the hotel for some relaxation and some time in the pool.
There's nothing worse than pushing the limits of what your kid can handle. Just my opinion.