I think that every girl needs a black and white striped top in her closet. It goes with everything from colored pants to skinny jeans to skirts: versatile and basic but fun.
I almost did a double take when I saw the Forever 21 version on the right (available here) because it's so incredibly similar to the lovely J. Crew one (sold out, but was available here). Seriously, what more could a girl ask for?
The 'grey melange loomknit sweatshirt' by J. Crew (find it here) is another wardrobe stable. Yes it is just a sweatshirt, but it somehow adds class to whatever you wear with it, from workout pants to scrubs to jeans to black pants (not to mention it's super comfy). Love it over a button-down shirt.
I'm not sure if Forever 21 is purposefully making replicas of the J. Crew loveliness, but this grey melange top available here is very similar again to the J. Crew one. It;s probably not as substantial as the J. Crew one, but at $14.50 I'm not complaining.