Apparently I'm in the minority here, but I vastly prefer to play Lem towards spellcasting, to give the fastest exploration and deck recharge.
your approach should certainly adapt to the party. if you need to be able to combat, definitely choose weapon and pick a location with monsters. If you need to explore, get some crafty spells and go for a location with a smaller monster count and no punishment for undefeated monsters.
One of the coolest things about this game is that you don't just need to worry about beating monsters, you have to worry about beating the clock too.