For the Beemer, consider Autohaus Bayern in Beaverton on Rt 10 Beaverton-Hillsdale, just east of 217. They specialize in BMW but also did a pretty good job for me with my 993 Targa. I've seen Alfas at The Jag Shop on E. Burnside at 60th; don't know about Lancias or Fiats. The owner, Craig, a member of F-chat with a 456 and a 430, does a lot of Ferrari work. Both firms a reasonable in their charges and stand behind their work.
There are a bunch of German car repair shops in Portland, all with their own fans. I'd pick the one most convenient to you. For me, it's Motorsports International, on Cornell Road. I've been using them for 20 years now. I don't know if they are necessarily better or worse than any others, but I can walk to them from my house, and my cars still run okay after all these years. For the Italian cars, Craig is good, and I'd also consider ATD.
Thanks Allan and Don, yes we at the jag shop would be happy to work on Alfa's but sorry on the other cars. Two of us at The jag shop have extensive Alfa training and experience 503-731-9919