I'm not really into 3some/4some fics, but I read one a long time ago that was pretty good. I loved the dynamic of their relationships with their own wives, and then all 4 of them together.

No I in Foursome (http://infatuated-ink.livejournal.com/48180.html)

While on the search for that fic, I found 2 others I liked and thought I should share those as well:

Let's make a sandwich (http://latentfunction.livejournal.com/401608.html)

We Warmed Up To So Many Things We Never Could Have Made (http://waterofthemoon.livejournal.com/517070.html)

(Sorry all of these are one shots and they don't have everything you're looking for, but I hope they're still somewhat useful.)