24 hours is up, so here's my most recent update
I was able to get the ticket i was looking for - in the end i went "Premium Economy" on Lufthansa. Under $1200, and that includes two free checked bags each way, which I was going to have to pay extra for when going regular economy, so all-in i'm probably only out ~$200 more than I had hoped.

Booked everything on Lufthansa.com. There's a United flight to Chicago from my city, then four Lufthansa flights:
Chicago to Frankfurt (Premium economy class N)
Frankfurt to Athens (Economy class Y)
Athens to Frankfurt (Economy class Y)
Frankfurt to Washington IAD (premium economy N)
Then from washington there's a United flight home.

When i plug those 4 flights into the flight calcualtor, surprisingly the "Y" class gives 150% RDM earnings!
So with just those 4 flights i'm at 11,813 miles RDM, 2,178 PQP and 4 PQFs.

I can log into United.com and using my Lufthansa confirmation code, can pull up my full itinerary (it shows up in 'my trips' - i'm assuming because i entered the MileagePlus number at booking).
United doesn't show anywhere on their itinerary what my PQP will be for the two flights in the itinerary that are on their airline, but i'm assuming that's got to do with what their 'list price' is, so it will be hopefully 100+ PQP each, but no way to really know?

I was pretty proud of the amount i paid for the higher PQPs, hopefully going to be at 2500 PQP for a <$1200 itinerary, in premium economy.
Let me know your thoughts, and whether i'm calculating it correctly please