I haven't seen as many movies with him in it as I should have. But I loved Uncle Buck, Planes, Trains & Automobiles, as well as Spaceballs when I was a kid. And Little Shop of Horrors too, though I can't really remember him in that. Great actor for sure, a really comfy comedian.
Planes, Trains & Automobiles is one of those funny movies where critics and audiences like it just as much as each other but because of the genre it's in (as well as maybe some of it's 80's cheese) it will never be given the acclaim as a masterpiece, which it deserves. It is genuinely one of the best movies I've ever seen. It's comedy is well written and the film has a very nuanced meaning to it, sure the last portion of the film can really only be interpreted one way but once you finish it the first time the entire aura of the movie changes.