Tough call. As I've been flying lots of domestic crap lately (and it sounds like the OP does too, given the fact he's gone once a week), I've come to the realization that:

(1) First Class is nice, but getting on an earlier flight to get home is better...even if it means Y...and even if it means a middle seat in Y.

(2) Schedules are key. Case in point: Monday I had to fly ORD-DCA. The 8am UA flight was sold out...my only option was a 6am. I took the US flight at 8:25, and slept an extra 2 hours. Didn't miss UA one bit.

(3) Comparison shopping. It isn't as frustrating when you "share the love" between airlines when you see ORD-LHR on UA is $600 and ORD-LHR on AA is $400. Simple choice, just take AA.

That said, 1K on UA does earn you CR-1s, SWUs, and decent waitlist chances. I guess it depends on how much you value these things. If E+ is what you're after, 1P is basically the same as 1K in that regard.