I've done solo trips to WDW, and one to
Disneyland, August of 2003.
Since you asked about Disneyland...
I booked Candy Cane Inn online. I had a terrific rate for 4 nights, and when
it's 100 degree weather, the air conditioned shuttle is the way to go!
I would have walked had the temps been in the 80s.
The best part of going solo at Disneyland: Single rider lines!
It was incredibly busy, but so many attractions had single rider access,
even if there were no dedicated single rider queues. It took me a few
hours to discover this treasure. Indiana Jones at a 200+ minute wait?
Nope! I found out that single riders can head through the exit,
up an elevator, around a corner, down the other elevator....and in
the loading area. (Sure, you bypass the cool queue, but I've seen
the queue before. LOL).
If I didn't see a sign for single rider entrances, I'd just ask any
cast member working the attractions. I must have saved
hours upon hours.
Also, I was able to dine solo at the Vineyard Room at DCA and Napa Rose
at the GC. Yum.