A solid hardwood (e.g., maple, walnut, cherry, or others) will be much
stiffer than Baltic birch or other plywood, and is a better choice for
thin shelves that need to bear weight.  It also avoids the problem of
edge banding or laminating a strip on to hide the raw ply edge.

Along the same lines, many headaches can be avoided if, instead of
trying to finish poplar or pine to "look like" walnut or cherry, one
simply uses walnut or cherry!  In the context of most projects the
added cost is minor relative to the hours invested.

Cheers,
Roger Wiegand
http://www.carouselorgan.com/