If it moist enough, the bee balm will take over all by itself. It can be a very aggressive spreader in moist soils.

Sage (and other salvia), Lavender, lemon balm, mint (careful mints spread like crazy), did I mention lavender. The list is much bigger than this, but you'll get a massive response from these plants.

With three hours of sun lavender and many of the salvia cultivars won't do very well. However, there are so many salvias that I bet some do ok in part shade. You could have a fun monarda garden- a dozen varieties will do ok, if not thrive, in part shade. You have a long growing season, so think about covering the season from early to late bloomers.

In a sunnier part of your garden try the plants beegeek suggests.