When the monorails are not crowded you can joyride and visit resorts.
Many people will say that resort guests include resort visitors.
When ID's are being checked at the monorail station, you must have an ID for a resort on the monorail line, although sometimes the checker does not catch this. There is a resort code embedded in the serial number of the room key.
The official policy has such statements as off site one day (hopping not allowed) ticket guests may not use WDW transportation, but the defacto policy is that, except where there is overcrowding, the only thing that keeps guests off of the transportation is not having anything to do at the destination.
However you should expect to be shooed out of the pools of a resort you are not staying at.