Hi bkorth, if you want a uniformed sleek look I would suggest square frames. Hate to say but look at ikea!! If you want a more eclectic look you need to shop around for different styles and sizes. You can still keep to a single frame colour to tie it together. The easiest way is to place them on the floor and play around until you like how they all go together as an image. I suggest that the end shape is a rectangle if that makes sense. if you need an image let me know.