We're going to do two strollers. DD will be almost 3, DS will be almost 5 when we go in April/May. DS has a lot of endurance, so I'm thinking he'll walk a good part of the time, but we want to have one there for when he needs it. We also want to be able to split up if needed. We'll be taking our larger single stroller (Graco Metrolite) - we can put stuff underneath in the basket, etc. The other will just be an umbrella stroller. I figure if DS wants to walk, we can fold it up and place it "above" the basket of the other stroller, under the seat. It will stick out, but it's still managable. Our water park day, we'll likely only take the one.
of course, we are driving, so we can take whatever we want. If you're flying, not sure how that would work.