If you have a car you should visit both Knitch & Why Knot Knit. Knitch is in Virginia Highland, which is a little pocket neighborhood northeast of Downtown. Why Knot Knit is in Buckhead.
If you need easy directions to either feel free to PM me and I'll send them over to you.
Oh - and while you are here and since you are in Downtown - if the group you are with wants a great place to go for cocktails - I highly reccomend Trader Vic's. It's in the Hilton on Peachtree - it's a very cool themed place with super fun drink and appetizers.
Enjoy your visit to Atlanta!