Brookside Gardens, a Montgomery County park, has a lot of what you want and is a beautiful walking area. It's undergoing a pond reconstruction and parking lot renovation now, but check it out. They also have an associated woodland garden (azaleas, etc) in Bethesda MD.

Here is a link that might be useful: Brookside Gardens

Thanks, Shady! It's actually right at the top of my list. Apparently there's a grat nursery not too far from there, "Susanna's Nursery Farm", that specializes in dwarf conifers and JM's. I'm hoping I can visit both in one day. Have you been to it?

You can never go wrong with a trip up to Longwood, if you've got the time. Their exhibits are jaw-dropping any time of the year. Ladew Gardens in Monkton, Md is also nice, especially if you want to see some cool topiary. Lastly, my husband and I just day-tripped to Winchester, Va yesterday and visited the Museum of the Shenandoah... We were surprised to find some lovely, diverse and enchanting gardens on the grounds of the Glen Burnie House, which are adjacent to the grounds of the museum.

About 1.5 hours from Baltimore is Mt. Cuba Center in Hockessin, Delaware. Their focus is on native plants and their cultivars. Beautifully landscaped former DuPont family estate, extensive trial gardens. Obviously, they're not going to have the Japanese maples and hostas, but lots of inspiration for landscape plantings that are ideally suited to the environment in our region. They may also have some tips for co-existing with deer.

Here is a link that might be useful: Mt. Cuba Center