Original poster of this thread....
Just got back from
Disneyland. We have a side-by-side City Mini stroller (
http://www.babyjogger.com/city_mini_dbl_dtl.aspx)
BRING IT! It helped us so much and fit through every door.
We also bought and brought a bike lock so we could chain up our stroller when we felt it may get taken (Downtown Disney I trusted a bit less than in the parks).
BRING YOUR STROLLER. I can't stress that enough.