When I have stayed at both resorts I have seen
ECV's parked in the hallways outside the rooms of the guest who used it, so that's what you would have to do.
Now as for which one you should pick I would go with the Boardwalk because in my opinion they have the best theme/atmosphere among any WDW Resort, plus you also have walkways/Boat transportion that goes to Epcot and Hollywood Studios.
However if you picked the Contemporary that would also be a great choice since their rooms are among the biggest of the Deluxe Resorts, along with the Resort Monorail access and walkway to the Magic Kingdom.