Ulta's 21 Days of Beauty is great if they're offering sales on brands you like! I think one of the things that I like best about this is the fact that a lot of the sales are on what they refer to as "prestige" brands, which is really all I purchase from them. As you already know if you purchase from them, their coupons don't typically work on "prestige" brands, so this is a rare opportunity!
What day/days are most exciting to you? I'm really looking forward to the day butter LONDON is on sale because I have a serious thing for these fabulous polishes!
I pulled this directly off of ULTA's site: