Hmm.

I use "y'all", but being Southern born and bred, it's natural to me. :) I use "guys" as largely gender neutral, but only use it when for whatever reason "y'all" doesn't work. And in the example above, instead of "those guys over there," I would probably say "those ones over there," though upon reflection I have no idea why, or "those folks over there."

"Dude," however, for me is used largely as an exclamation and is entirely gender-neutral -- "Dude! You totally just stole my drink!" or "Dude, don't buy that! I've got one I'll give you!"

(Only tangentially related, "buddy," "babe," and "sweetie" are also gender neutral for me, which I only really noticed when one of my male WoW guildies expressed some surprise at being called "sweetie". :)

And I accept "mankind" as typically intended to be gender neutral and it only makes me cringe a little bit, but I prefer "humankind."

I only use "peeps" with a small handful of close friends, 'cause it feels like stealing language the same way that it sounds like "y'all" feels to you.