Working east to west:
Budapest, Bratislava Vienna, Linz, Salzburg, Munich, Innsbruck. Then take the Brenner Pass south to Lake Garda, Verona, Venice, Trieste. If you're willing to go further north, I'd highly suggest going further into Bavaria. Bamberg (where the beer god's reside), Nurmberg, Regensberg, and hook into Czech Republic for Plzen and Prague, you won't regret.
PM me if you'd like some tips on certain cities.