The movie under the stars is right there at OPR, near the pool bar. Its actually a lot of fun, dh and I did that one evening last month. We grabbed dinner at the food court, ate outside then they started the movie (It was Tangled the night we sat there). They set the movie up right in that courtyard near the pool bar Mickeystoontown mentioned in her post. They have seating set up or you can see it from many of the tables. We left a bit early to take a walk and watched Illuminations from the beach area in Jamaica.
Downtown Disney is easily accessed and there is shopping, a movie theater, lots of dining and its always fun to head there.
I will also admit, dh and I brought a DVD player and hooked that up to our tv in the room. A couple of nights we headed to our room a bit early and just chilled with a movie in the room. We were there 11 nights and we just didn't feel up to doing the parks every single night. I think we did three resort nights total over the trip.
Downtown Disney is always open late, the Boardwalk, I can't remember for sure but its at least 10:00. If they did the Boardwalk, they could see some of Illuminations from that area as well. The only problem with Boardwalk, is they will need to take a bus from the Boardwalk resort, to another park or DTD, then transfer to a CBR bus. DTD they can take a bus directly to and from CBR to get there and back.
Good luck, you are a very sweet son and brother to research this to give them an idea of what they can do on nights they don't feel like eating dinner!