Hi there! :) There are plenty of awesome things four hours from DC. (The lovely Raleigh Durham area, for one, towards which I have a strong personal bias ...)
I'd love to work something out with Snape - I'll be around most of tonight, and will keep a lookout! I'm sure Lucius wants absolutely nothing more to do with Diggle, but he doesn't always get his way. ;) Longbottom he doesn't have much of a problem with, although he wouldn't really have known him at school, being a few years older.
Barty! Lucius would certainly know him, and probably even like him - he appreciates ambition and probably isn't at all fond of Crouch Sr. And how could he not at least pretend to be buddy-buddy with the Minister's assistant? He can't pass up that sort of opportunity.
As for Montague, any well-connected career diplomat with the right pedigree and politics and a cabinet-level position (er ... wizarding equivalent of cabinet-level, anyway) is good in his book, hands down. He's probably trying to get on her good side already, and might be annoyed to find out that his wife is trying to do it for him, behind his back. (Not that he wouldn't take advantage of her efforts in a heartbeat, of course!)