I love Sephora! I'm actually quite addicted. I'm always approached by an associate when I walk in the door, and they've *always* been able to answer my questions--or at the very least find someone else who is more knowledgeable about the product(s) in question. I never leave unhappy or empty-handed. ;) Their Beauty Insider program is fantastic and has helped me to get acquainted with a lot of awesome new brands and products. They also give you samples when you check out, regardless of if you're a part of the rewards program. Free perfume samples? Heck yes!
Anyway it's pricey and a bit high-end but totally worth it.