Okay, lets see from memory
Star tours does have a fairly convienent exit, or they will just let you go through the cabin and out to the other side. This one exits in the Star trader store, and there is a bench right by the exit.
Space mountian did have a convienent exit (I think it still does, I just haven't looked since they redid the ride). This one exits near the arcade behind Honey I shrunk the audience. There are benches here, and restrooms.
Autopia you could easily exit, but it would require going down to the bottom of the stairs and then back up again, they won't let you wait down where the cars load. This is next to innoventions so you can go in there and cool off or relax if you wish.
Matterhorn, fairly easy to exit, but line is nothing special. There are plenty of benchs outside the entrance to this.
Thunder mountain, this would require you to walk through the ride car to the other side. It could be done. The exit is located up the hill to the left of the entrance. There are benchs out by the entrance, and a few by the exit.
Indianna Jones, You can walk most of the way through the line. I would get out of line at where they take the wheelchairs out right before going up stairs. This line is a nice walk with things to look at so it might be nice. Exit is near the entrance, again there are benches plus the stores across the way.
Splash mountain, You would have to walk up a few stairs (4 maybe) over the boats, and back down stairs. Not a real pain, then you could wait in the room where the photos are shown. Or you can enter through the exit to see the photos. The exit is located all the way to the far end of critter country, and then to the far left (if you are facing the shop) There is a shop outside across from this exit, and some benches.
DCA
Tower of Terror, I don't remember where I went, but I have walked through the line and gotten out right before you enter the elevator. You exit to the area where the photos are, and then into the shop. Benches are outside the shop.
Soarin over California, While I'm sure it's do able, I wouldn't bother standing in line, espeically inside the building. The exit is near the entrance, there are benches, plus it's right next to taste pilots, and not too far from Burrbank Ice cream for a snack.
Grizzly river run, if you don't have fast pass it will be a long line, and nothing special. Getting out will be a pain, unless you leave at the point where the fast pass people enter. With fast pass the line is so short it's not worth waiting. There are benches in the area, plus a store right next to the ride. If he is standing in a long line (hour or more), and you want a break, I would walk through the GC entrance right near there, and either go get a snack at white water, or go sit in the lobby and relax. I love to sit in the fireplace, and we often choose to go sit and rest on hot days in here. My daughter while go back and forth between the TV set in the corner with cartoons and the fireplace. They also have storytellers come, though I think its usually more at night.
Mullhulland madness, I'm not sure about this one, you might have to go through the ride car to exit, it's been a long time since I've actually been on it. Line is no big deal and there are lots of tables and benches around.
Maliboomer, I think you could easily exit. There are a few benches but not many right there, there are more closer to the sun wheel near the stores.
California Screamin, I think there may be an exit right before going up the stairs, but I haven't really paid attention. Benches are closer to the water.
Did I miss anything you are thinking of not riding.