I usally have the crystal on the back, unfortunetly its not smd and I don't like cutting the pins flush on the other side to fit the ic flush still
another thing about most smd is that the fets and transistors are meant to lay horizontal and take up more space than the same dip that can go vertical, I've seen it done on my old cars ecu actually they had some smd components on a smaller pcb that was soldered perpendicular to the main board just to fit more, I think I may copy that technique for a board or too I have in mind