Just thought I'd chime in with my two cents!
My brother and I have been the past 3 years in a row, the 2nd or 3rd week of June (not sure what "season" that is). We always take one day off in the middle of the week and resort hop. This past June, we rode the bus to the MK from Dixie Landings, then hopped on the resort monorail and rode it to Contemporary, then Poly then GF - no questioning, no ID check, not even a second glance.
I've read in tour guides like Birnbaum's and Unofficial Guide that they suggest you carry your resort ID because the use of the transportation system is a "perk of Disney Resort Guests". Bull :lol: WDW transportation is treated anymore just like any city's transportation. It may be policy to check IDs, but they don't. Any Joe Schmoe can hop on a bus, boat or monorail and ride till their heart's content.
Now, my little soap box - the people who have paid the big bucks to stay at a Monorail Resort should have first dibs on the Resort Loop at park closing and opening. That's a major perk for those $300 rooms, and I think us schlubs should only ride that loop in the middle of the day, when it's not a mass entrance or exit - it's only common courtesy