Just as I was all decided to just rent a stroller every day for DS 4 1/2 I started thinking that it might be really nice to have after a long day at the parks going back to the room, etc. How hard is it to get on a bus or Monorail with a stroller?
We found it to be only a very minor annoyance to take our stroller onto the bus system. It takes but a second to break it down and take it on board, and it was nice to have to take our toddler to and from our room to the bus stop. In fact, we'll be taking it on our next trip as well, we liked having it so much. However, our dd only just turned 2 so she is still quite young and it's hard for her to walk a lot without getting totally tuckered out. If she were older we might just rent a stroller as she could probably walk those distances to and from the bus stops.
Here's another vote for an umbrella stroller (for the cost of renting a stroller daily, you can get a decent umbrella stroller). They're great to have after a long day in the parks when walking back to your room. We have one with a shoulder strap which is convenient when nobody is riding in it.