If you can venture further downtown (about 10 minutes on the R train), get off at Prince Street and go to TopShop and Allsaints, they're 2 British brands. The stores are great, and they're currently having sales (not sure how long they'll last).
And I'm all for 5th avenue! So many great stores there, its not a bad walk at all.
Also, if you dance, go take class at Broadway Dance Center on 45th between 8th and 9th Avenues. Classes are usually an hour and a 1/2, they're $18 each.