Recommended Wood For Cabinets

[rec]

Hi! We're in the process of converting one of the twin beds in the back of our Airstream into a desk. We've got the plans all laid out (nothing particularly complicated), and since we've done a bit of woodworking in the house we are going to try to build the desk ourselves. However, I want to know if anyone has suggestions as to WHAT wood would be appropriate to use. When we go to Home Depot or Lowes, we see endless varieties of wood, and have no idea where to begin.

We're going to do the desktop itself in a custom laminate piece, so we only need wood for the body. Basically, wood for vertical supports and a flat surface underneath the desk that will enclose the exterior storage area and provide shelf space.

Obviously it needs to be light and strong. We're also going to paint it, so it needs to be something that can be finished smooth.

I can provide a sketch if needed, but if there are any quick recommendations for this, it would be appreciated. Thanks!