I have a group that's getting a bit bored with the standard 4 classes. They're asking me if there are classes that could be skipped in lieu of some more interesting support roles in more recent books. What base classes do you feel, if left out, would portent failure for the group? What base classes do you think could be skipped? Lastly, are there any you feel could be multiclassed, such as the rogue, and not get them into trouble?
I'm also a little worried about allowing a druid and ranger in the campaign after briefly skimming through the modules and not seeing much in the way of wilderness scenarios.