I've got lots of experience figuring out how to have a good time despite my limitations at WDW. But I'm new to DL, and I'm new to the current neurological symptoms I'm having.
I've been to
Disneyland once, and at the time, I was not significantly neurologically impaired, but I had a back injury and some trouble walking. I used a cane and had a GAC to avoid stairs, and didn't ride anything very intense. Now I'm planning a new trip, and I'm trying to figure out what the best way is to handle each attraction.
I noticed that for some attractions, the alternate waiting area was "worse" for me - more chaotic, more tightly packed, longer waits than the regular queue. Pirates of the Caribbean was bad enough in the alternate area that I just couldn't do it. Now I know I should do PoC much earlier in the day than the wait-time apps suggest.
Are there any other "Gotchas" using the alternate entrances that I should be aware of? (More crowded, more confusing, tend to have much longer than posted waits, etc) I know things change a lot, and GACs aren't always handled the same way - I'm just trying to put together a touring plan that doesn't lead to "Yeah, you guys go through the regular entrance, and I'll meet you when you're done."
Also, one of my medications makes me photosensitive. At WDW, I didn't need to ask for accommodations for shade, I just wear a big floppy hat and sun-protective clothing. But, at WDW, most of the queues were shaded, and I could usually cross the walkway to catch some building shade. Is DL equally shady?
To answer the last question first - there is a lot less shade at DL in my opinion - you cannot even count on queues being in full shade all the time. Also, many shows are in the open air, so even though there are tarp-like shade, there is a very great deal of ambient sun light. Most benches are not in the shade and most table service restaurants have outdoor seating, also not necessarily shaded.
If you need the wheelchair accessible entrance or whatever alternate entrance may be available, that will increase the amount of time you are in full sun. The accessible lines (which are different at least in part from the mainstream queue) for Haunted Mansion, POTC, all of Fantasyland, and especially Small World, the Railroad, Jungle Cruise, and potentially others, are in full sun. Most queues at DCA will have you in the sun at least part of the time, and even FP will not help you avoid this. I do not think there is a GAC to help wait in a shady area (at least there was not last time I asked Guest Services), as there is literally nothing you can do to avoid sun in queues in Disneyland.
You will need to plan to wear full sleeves, a big hat, and LOTS of sunscreen. Others here on the boards are photosensitive, so they will have some ideas.
Honestly, having been to both parks many times (at DL several times a week), I can say that it is very difficult to plan for accessible entrances. I ask about accommodations for rides, even if I do not use them, just to know. And I can tell you that the "alternate" entrances for rides vary wildly from day to day, and some rides do not have ANY alternate entrance option - sometimes the mainstream queue is it.
I CAN tell you about wheelchair accessible entrances that are different from the standard queue, and if you are planning on visiting at any crowded time of year (summer, spring break, christmas, etc), almost all "alternate/accessible" entrances I have experienced are MORE crowded or louder or hotter than the standard queue. Very few rides have FP in Disneyland or DCA as compared to WDW, so that makes it harder too.
DL and DCA are very different in age, so obviously their queue structure will be different too. So I will handle them separately. Also, if you have any kind of GAC (I have had one for years with a variety of stamps depending on my needs at the time), they will be handled very differently between the two parks due to this.
In DL, the wheelchair/accessible (meaning no stairs or turnstiles, etc) entrance is almost always the exit. This sounds like "instant access" but there will almost always (even in the off season) be a line of people with a need of whatever kind also needing that entrance. DL shades the queues INTO rides, but really does not shade most exits. This means when we are waiting our turn to ride (most rides have a limit to the number of wheelchairs allowed on at a time - anywhere from 1 to 3 usually), you are waiting not only in full sun, but also where people are trying to go out. In many rides, it is not even a wide enough space for two wheelchairs to pass, so sometimes it is VERY crowded. Often times we are not in queues but waiting in a "self made line" outside an exit (usually this happens in Fantasyland) in the main walking area.
The most popular DL rides like HM, POTC, Splash, and a few others have an accessible queue, which is generally a line on the side of the main walking area, sometimes but not always roped off with just posts and plain rope - especially during moderate to crowded days, the line can be longer than the standard queue and is right in the middle of walkways and shop entrances. I do not even try riding these rides when it is at all crowded (which means I almost never ride really) because these are very loud, very slow moving, very crowded, and VERY HOT!
Some lines are mainstreamed, so I am not sure how any alternate entrance that may exist would work for these rides, but again, not all rides have alternate entrances. If you cannot access the main queue line for whatever reason, mobility or other, on most DL rides the only option would be the wheelchair accessible line through the exit. Really that is the only way into the rides other than the main queue. Honestly, I hate some of the lines - trying to make your way through the dark (very very dark) exit against the tide of people into Indy can be hard.
Oh, and the wheelchair accessible entrance for Space Mountain is one of the worst places to wait if you have problems with loud, crowded places - it is also the exit, the restrooms for the area, the photo/tshirt purchasing area, and the arcade/wreck it ralph M&G.
DCA (which I visit less often) has more options when it come to accessing rides, but no guarantees there either. And in my opinion, you can count on shade even less in DCA than in DL for queues - all queues have shade somewhere, but they are not covered or indoors the whole time like in Florida.
All of this sounds very discouraging, but really you CAN do Disneyland. I have just found the GAC to be of limited help when it comes to accommodating my needs like ADHD/anxiety/claustrophobia. Frankly, Disneyland is just too small for them to have too many queues going at the same time.
Make use of FP when you can. Be aware that having a FP for some rides in DL will not be useful if you also need the wheelchair accessible entrance. FP queues are not always accessible, so ask the CM when you get to the ride.
A touring plan will help you more than anything. Having a good idea of the best times of day to try things is invaluable. For example, when it is at all crowded, I do not try to do POTC or HM unless it is early morning or until twilight/evening, so I am not in full sun in the queues. During Fantasmic, NO ONE rides Jungle Cruise. Some lands are not as crowded during fireworks, etc.
You really can have a great time. Try to find indoor or at least covered shows to go to during the heat of the day. Go to the late parade, when the sun is going down. Maybe even take a break during the day so you can avoid the worst sun. Several of the character M&G are indoors or in the shade, so those are good for during the day.
I really do not mean to sound discouraging. I just don't want you counting on a GAC to do things the parks just aren't designed for. I am not sure what your current limitations are - mobility or different kinds of invisible issues - so I can't tailor the information... but if you can tell us any more, we may have some ideas!
I really hope your trip to DL works out - when are you planning on traveling? That will also make a difference in the advice people have
Sorry this is so long!