I recommend Fat Quarter Shop for solids. They have a 'shop by theme' option and you can look at all their solids and near solids together in one place. I used to prefer Michael Miller Cotton Couture, but lately I've tried the Art Gallery solids (I think these are called Pure Elements?) -- I love the feel of Art Gallery fabrics. My new favorites are the Riley Blake confetti cottons -- such wonderful colors and so soft after washing!