I finally got a pretty cool itin:

SFO-DUB-DCA then IAD-ORD-SFO (with requested overnights to visit friends in D.C. and Chicago) for $605 on US Airways. Okay, so it's hardly my airline of choice and it involves many plane changes, but still... pretty good price for Dec at last minute!

Here's how I did it.

1) First, identified which European airport would be cheapest to dash to and from. Given my flexibility in dates and lack-of-caring of which European city I went to (since it's just a turnaround), I used ITA's month-long tool as follows:

FROM: SFO;SJC;OAK
TO [in sets of three, so as not to overload]: cdg;ams;mad
fco;zrh;bru
mxp;bcn;man
arn;cph;dus
ist;osl;vie
svo;txl;dub

2) Dublin came out as the cheapest by far, along with specific days highlighted (Dec 8 and 13).

So, keeping direction in mind, I then tested out SFO-DUB-IAD-CHI-SFO itineraries for both Dec 8 and 13 (again on ITA) and got a fare of $600 after hand-picking the segments.

3) Booking time! Tried Kayak, but 'twas no go; priced way over $600. Then tried US Airways site (man, you think .bomb is bad? gah!) Again, with my desired flight times as selected via ITA, it was way over $600.

So then I decided to be crazy. I called up a US Airways agent and had her price it... and it came out just $5 more then ITAs stated $600 fare (+ $10 for the phone agent fee, for a total of $615).

Pity I couldn't book this online, 'cause then I could have taken advantage of US Airway's current European promotion: 10% off + 10K frequent flyer miles with European round trips flown before Dec 17. Oh well.

Anyway, for about $600 and the inconvenience of an overseas dash, I'm getting:
...to visit two friends I haven't seen in ages, albeit briefly
...over 20K frequent flyer miles on United (double miles due to 1P status)
...1K status on United

(I would stay in Dublin for a bit to explore, but my company's European headquarters are there, and I'll have the pleasure of a Dublin visit in February again anyway).

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Whew! Hope my discoveries / musings here are helpful to someone :-)

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P.S. -- I have put a hold on this 'til Tue at midnight, so if by wild chance you know of a much better option, let me know before I ticket this. And yeah, I'm guessing I could have gotten a better miles-bang for the buck by doing a couple of domestic itins, but this is more efficient time-wise I think.