Georgetown Park is a pretty good mall. Compared to other non-suburban DC shopping areas, its great. It also doesn't hurt than Georgetown has many shops surrounding the mall that help fill in the shopping 'gaps'.
As for stores, some of my favorites are the Victoria's Secret, Anthropologie, H&M, J Crew, white house/ black market ,,,there's a full listing at www.shopsatgeorgetownpark.com. One of my favorite stores EVER is a little store on the second level called Fornash (www.fornashdesigns.com). Its a girly store that has lots of 'choose your fabric and ribbon' options to make purses, belts, watches, etc.
There are also a lot of eccentric type specialty stores with goods like scarves, hats, or gifts in them...I'm sure they're great for people that love that kind of stuff, but I think its one of the big downfalls of the mall - there are just a whole bunch of shops that seem to serve a very small population of buyers.
The parking is an added bonus - I think you can validation for a $5 or $10 purchase which means no driving around on bumpy cobblestone roads looking for parking for 1/2 an hour...which means, extra time for shopping!
All in all, I'd give the mall about a 6 out of 10....8 out of 10 if you take into account that it only takes about 100 steps or so after leaving the mall to enter into Restoration Hardware, BCBG, Coach, Uno's, etc.
"The one who has the most purses wins!"