What is the limit to the laid-back look, before you look blah?

Make sure even though your clothes are laid-back, they're fitted so you still look cute not like you're wearing your man's clothes. When I dress laid-back I try to wear my hair down and accessorize well.

When it comes to those days, I pull out the sweats and the graphic t's. Or sometimes if I have a matching jacket, I wear a tank top underneath

I think, if you want to be relaxed and low maintenance, stick to clothes that are comfy, easy to pop on, like jeans and a t-shirt and some sneakers that you think are kind of snazzy. To remain feminine keep the t-shirt loose but close enough fitting that you curves are shown well, and cool graphic t-shirts I think are a good way to go. Also add a "something else" that you really like, something simple like a ring, necklace, hat, belt, or sweater that gives your outfit a little more style. That's how I do it at least.