>>Sometimes, when I want my character voices to be distinct I pick friends of mine and assign their voices to characters.<<

That's a really clever idea! Thanks for sharing. I rarely need that sort of thing myself -- a majority of my characters emerge quite distinctive -- but I bet lots of folks will find it useful. I do sometimes pick a regional, class, or other dialect/register to color a character's speech.

>>Otherwise I have a few basics... but it's really hard not to slip into 'generic dialog' mode where everything could have been said by anyone because it's all... generic.<<

I find that I am quite conscious of word choice. I often know that what I'd say and what a character would say are different. But part of it is just all the internal translation I do, going between one world and another.

>>Also hard not to do nothing but write dialog and dialog and dialog with no descriptions of anything or anything happening. Okay, that sentence was horrible. Anyway, that's especially annoying because I can clearly see what's happening in my mind's eye, and what everything looks like, but when I try to describe anything it comes out awkward.<<

Have you tried the exercise where you watch scenes in a movie or play, and then describe the action? That can really help develop description skills, especially as those interact with dialog.