Planes, Trains, and Automobiles was (and IS) so damn funny it's become a staple for me every Thanksgiving. There's parts that make me laugh, make me cry, and make me fall on the floor holding my gut. That one scene in the car where Steve Martin's character turns to John Candy's character and sees him as the devil...oh lord...
Stripes is also a "classic", as is Airplane!, Caddyshack, and several others in that genre alone. There's no way Hollywood could ever make Blazing Saddles again with the same lines that they used back then for fear of upsetting too many different groups, but I think that's part of the wonder of the movies made then.
My kids (3 teenagers) will watch some of those 80's movies with me and just wonder what the hell we were thinking by watching them back then -- the special effects are cheesy or whatever. I tell them that they have grown up in a generation where things have become possible that were impossible just 20 years ago but they still don't get it. All I know is I still enjoy lots of those 80's movies.