Here is a link to the official
Disneyland ADA guide (aka mobility and other similar issues).
https://disneyland.disney.go.com/guest-services/guests-with-disabilities/
If you scroll down just a bit, you will find pdf files for each park, in where they describe each attraction and the issues.
Since Disneyland is a much older park, there are issues like stairs, narrow walkways and other issues. The attractions that have been remodeled/upgrade or recently added in the park usually have good access.
At California Adventure, there are very few issues, as the park was built after the US ADA laws were passed, and you have many rides designed for even special loading systems to be able allow those in wheelchairs to even ride with the wheelchair, though some still require what is known as "transfer" where you would be able to get out of the wheelchair and deal with a few steps and being able to sit in another seat.
But Disney has been very good in trying to match a person's needs and how they deal with the access to each attractions.
One issue that some don't like, but is the law, the ADA rules are "Equal Access" not front of the line access, and why for most alternative entrances you will need to get a return time to come back. Cast Members are posted and have a small smartphone like device that will use your ticket and scan the barcode and let you know when to return, the same basic time as the current wait.
But for some attractions, such as the Haunted Mansion, Disney is limited to how many ADA guests can be boarded at a time, in case the ride breaks down and that guests will have to evacuate the vehicles mid-ride, so the wait can be longer than the main queue.
So read the guides, here are the direct link to both the Disneyland and DCA guides.
https://wdpromedia.disney.go.com/me...eyland-park-disabilities-guide-2016-06-17.pdf
https://wdpromedia.disney.go.com/me...a-adventure-disabilities-guide-2016-06-17.pdf
Have a great visit.