If you can, go there often, and get really familiar with the place, so you know when you've hit on a great find!
The things I buy most often at Rack include :
shoes - but be careful, I've ended up with poorly fitting shoes because it's so hit and miss, and often you can't find the same shoe in a couple of sizes to compare the fit. The good news is that Rack has the same customer service/return policy that we enjoy at Nordstrom, and have been great about some of my "oops"'s
handbags - love my teal Furla and red Hobo bags
scarves, accessories
Paige premium denim
My teenage boys even "like" to shop at Rack!