I would say that, if you're going for a powerful party, that you should hang out in the Monastery for a while, at least until level 21, when chests that matter spawn better loot. You should be able to handle the Arnika Road, Arnika/Trynton Road, and Arnika proper after that. Note that Savant Slashers and Savant Minion will be waiting for you.

With these preparations, having raided Arnika, and being able to handle the high-level Savant machines, you should be able to get your characters to around level 30.

This will make the middle game trivial, up until the late game (when Ascension Peak enemies scale with the party).