British Airways flies to Sofia (daily flight in the mornings).
Raleigh as a hub? This is weird. Depending on where you are, there is a non-stop PHX-LHR flight (that cannot connect to the Sofia flight on the same day and requires a night in LHR) or there are a lot of connection flights via Dallas for example.

Redemption with Miles and More adds huge taxes and similar money... If you want to stay on Star Alliance, better find another program - United if you are in the States (or even the Air Canada one)... or one of the smaller European ones - such as Turkish. Not to mention that they dropped the percentages on what you get when you fly cheap paid economy...

If you are in a US Airways hub (and I just saw you are in Charlotte so you are), look at what you can find on BA/AA/US combined network before moving.

PS: I am flying back to Bulgaria twice a year as well so was just doing the same calculations last few months