You might join the UP playgroup listserv and ask the folks there.
http://groups.yahoo.com/neo/groups/UPplaygroup/info
My friends in UP are super happy at Greenwood. I don't know the wait list situation, but being a fed should help.
Other friends in that area rave about Heritage in Hyattsville, but I think that's a bit of a hike from the metro.
http://www.heritagechildcare.org/
Numerous buses go up and down route 1 (seriously, like 4 different lines - DC, PG, UMD, special rt 1 shuttle) , so St. Jerome's would be very accessible that way.