In the original plan I wanted two shelves. I re-worked the plumbing and everything for this design but ultimately decided against the two shelf design.
When designing your vanity remember, (Oregon/Washington) code requires the vanity edge (I took that as the counter) be 15 from the toilet center. My plumber Dad said inspectors let the toilet paper holder slide (most of the time). I think it's almost universal in the States. However, if you are unsure please check your local code.

I attached the legs (44's) to the aprons (14) to make the top of the vanity. I drilled two pocket holes into each 14 going into the 44's. I also added brackets, probably unnecessary, but why not? The 1x4s are flush with the top of the 44 and recessed in about 1/4

I used 1x3s for the bottom because they were significantly cheaper than the 1x2s. I attached each 13 with glue and two pocket holes. The side 13's at 11 10/16 and the front and back 13's are 26 3/16 (same as the apron 14 on top).

The bottom shelf is approximately 6 9/16 from the floor (you can change this if you'd like). Anything around 7 seems do-able for cleaning. The top of the shelf (top of 13) is 21 from the bottom of the 14 apron (again, this can be tweaked based on your preferences).

For the counter I attached two pieces of plywood and used Henry's feather finish on it. You can read more about the counter HERE!

ANNNNDDDDD......Here's the finished vanity!! I used Minwax Dark Walnut stain on the base and a clear natural finish on the feather finish. The sink is American standard, and the faucet is Pfister 4-inch Faucet. The Pottery barn version will set you back about $1899 + $75(shipping) +tax, while this version cost us about $390 and some sweat ;-)
If you want to see more about this bathroom remodel come check out the blog at Ginger and the Huth and search powder room