My son is CVI as well and is 5 years old. He definitely has some useable vision though. Anyways, some things that I found- he hates characters up close- they scare him. But he loves the parades- he sees things that are moving much better than things that are stationary, which is common for kids with CVI. My son still has a fairly strong startle reflex to loud noise or unexpected touch (common for kids with CP) so a lot of the 3-D movies were not good for him (Tough to Be a Bug he hated) but he did like Philharmagic but I don't think he really saw much of it- just liked the sounds. With rides, we try to ride 2x in a row on rides that have a lot of visual input (like most of the Fantasyland rides)- sometimes we get off and back in line and sometimes they will offer to let us ride again since it is so difficult to transfer him on to the ride. Anyways, it seems like the 1st time seeing something he doesn't process it but the second time he sees it better. His favorite ride is Buzz Lightyear- he also loves Test Track but he is a thrill seeker! Does your son like spinning? My son loves the input of spinning so spinning rides are his favorite- Dumbo, Teacups, that type of thing. But I find that these are the hardest to hold him up on. My son didn't recognize any of the princesses or characters that don't wear masks- he wasn't afraid of them, he just doesn't get that they are a character, even when he loves the movie (like Little Mermaid). Playhouse Disney has lots of bright colors and my son loved the bubbles- I think wheelchair seating might be in the back though- we always transfer him out and get there early to sit up close.
Oh, I know something else I almost forgot- we learned to bring something for my son to play with/look at when pushing him in crowds- a bunch of "booties" in his face and crowded close to him was very overwhelming to him- but if he has a light-up spinny toy to look at, he does much better. Oh, and he HATES fireworks- I don't think he even gets what people are looking at- he just hears the loud noise and starts screaming. The thunder/lightning part of Haunted Mansion scares him too. Oh, and they shoot a gun on the Jungle Cruise- that bothers him. But the gunshots on Pirates don't- who knows? Is your son sensitive about noises? I think because of his vision issues and the CP, my son really fears sudden, loud noises but if I warn him ahead of time and talk him through it, he is ok.
Hope that helps. You may just have to try things and see what he likes and doesn't like and then try to see what the common link is- that's what has worked for us. Hey, one positive thing- my son doesn't see any of the toys or treats in the store unless you point them out to him so at least we don't have to deal with begging or tantrums about that!