I picked up some nicely made plastic figures today in the toy section at the local 99 Cent Store. I got a Mickey, Donald, Goofy, Snow White, Woody, and Buzz Lightyear. They also had Minnie and several other Disney princesses, and there should be a Jessie and Rex from Toy Story. The heights measure 2 1/4" for Mickey to about 3 1/8" for Goofy. They are tall for O gauge, although they might look good up front, employing forced perspective. I'm guessing they would work best for #1 or G scale.

I picked up a few of those a few years back and put them on my Casey Jr train that used to run along the ceiling in my son's room. They look pretty good for g scale, maybe a little small, but still looked great on the train. Especially for a buck a piece.

Disney store sells a boxed set of "Mickey Mouse Clubhouse" figures that really look great with g scale. There are 7 or 8 figures and I think they go for $10.