You need more than room for the chart. You need a little room for the other 'stuff'. Dividers, pencils, whatever, and room for a straightedge to overhang the chart a bit.
I know it's ugly, but a piece of thin, soft plastic or rubber is helpful so you can stick the point of your dividers into it without damaging a fancy piece of wood. I've had to flog the owner a couple of times on Breeze for poking holes in my varnish work.
Make sure it's near the electronics if you have repeaters below. We've got a radar/gps/fishfinder repeater at the Nav table. That does a couple of things: it keeps your 'official' navigator/tactician/'wherethefugawi' person away from the main unit at the helm, and gives him position, wind, depth, etc. at his fingertips. (It also keeps those same fingertips away from the unit the captain/helmsman is trying to use to keep from going aground.
Finally, make sure there's storage underneath the table for charts, dividers, rulers (OK--scales), pencils, sharpeners, pens, grease pencils and all the myriad other things that find their way into the nav table. We keep our guest flags, Oscar flag, and a dive flag there so we don't have to hunt for them. We also keep a flashlight and a multi-tool there so everyone knows where to find it in a real hurry.
Finally, we keep a neat, printed (in very large type) Mayday form that I routinely printed out just before we shoved off. Some of the information remains the same, but the Souls on Board, position, etc., change on each trip. The whole idea in this was that even someone who isn't familiar with radio procedure could read the printed form and pull the position numbers from the GPS repeater, which was directly next to the Mayday form.
Hope this helps a bit.