I would consider a 1/4 sheet cake from Giant. It was great for birthday cake.

If you want something fancy looking Praline Bakery is lovely:
http://www.praline-bakery.com/celebration-cakes/

I love the cakes at Les Delices on Gude Drive in Rockville.

There is a place called Creative Cakes on Brookville Rd. in SS but I don't know anything about them.

There's also the Woodmoor Bakery, but their cakes are just meh IMO.

Any suggestions where to get a communion cake for about 15-20 people. I live in Silver Spring but am willing to go into DC etc for a great recommendation