I'm definitely interested in going to Mt Cuba in late spring. I've been there twice before and love this place.
I'm definitely making a trip to Black Creek Nursery in East Earl, probably a week day in April.
My arm could be twisted to go see the peonies in bloom at Peony's Envy and any of the other places that Jill mentioned.
I like Monticello in Charlottesville too.
Easy local places to visit include
Dumbarton Oaks in Georgetown - haven't been but always wanted to go, probably fairly close to Lisa's house
National Arboretum - been a few times, would like to visit this year when the azaleas are in bloom
Meadowlark Gardens - been a few times, nice stroll, close to Muddy's house