I love, love, love POR!!! It was my first Disney resort, back when it was Dixie Landings!!! It is so beautiful there...I loved just walking around the resort. Anyway.....there is the boat to DTD. Very pleasant ride. Not quick, but pleasant.
The monorail is currently having it's hours curtailed due to construction at the GF. So, the resort/express monorail is not running to and from the MK/TTC from the hours of 11:30am to 6pm each day. Not sure how long that will last.
BUT...they can get on the monorail at Epcot!!! Take the bus to Epcot and then hop onboard. It will go to the TTC. You can stay on and then ride back to Epcot...when it returns to Epcot, it actually runs through Epcot itself!!! Really fun to do.
Or, they can take the ferry over to the TTC from MK, and get on the Epcot line that way...ride to Epcot, and then back to the TTC again. Or, get off at Epcot, tour Epcot for a bit, and then head back to TTC or take the bus to POR.
Anyone can ride the monorail....you don't even have to be staying at a WDW resort....much less a resort along the monorail itself.
Hope they have a ball.