One of my favorite parts of
Disneyland is that most of the characters are visible out in the park rather than having indoor meet and greets.
I usually see Mickey, Minnie, Goofy, Daisy, and Pluto meeting in town square, I think they also meet in their houses in toontown.
It's pretty common to see a princess or 2 meeting in front of the Mickey head at the entrance or just as you pass through the tunnels under the train tracks, they also meet at fantasy faire.
I've seen lots of random characters meeting at big thunder ranch.
The fairies meet at pixie hollow but if you don't want to wait you can usually get a peak at them from the astro blasters line.
Anna and Elsa meet by the carousel but aren't visible from outside and the line is ridiculously long.
I can't really help with times because I don't wait to meet the characters but even without waiting you will probably run across several just by walking around the park.