One route I do myself - it isn't vastly profitable, but takes you through 3 different houses, so gives the opportunity for RP along the way and still nets at least a couple of million profit each step.
Essentially it's Liberty Ale from Planet Manhattan to Planet New London. Gin from there to Planet New Berlin, and then you swap for Rheinbeir to bring back to Planet Manhattan.
Because it's relatively low-profit, most pirates won't normally bother you too much - but any "donations" they ask for usually factor in the lower profit you'll be making from the booze compared to ores.
