Can be dressed up or down (my absolute favorite kind of dress):
LOFT - 40% off site-wide, no code needed (runs through 3am ET on Sunday)
Old Navy - Entire store on sale up to 50% off
H&M - Free shipping on orders over $50 with code 3042
Macy's - Friends & Family Sale with extra 25% off (runs through May 4, exclusions apply)
Have a wonderful weekend!