I know there are some efforts out there to get web sites to stop using the www, but I still believe that a web site should resolve to the same place no matter if the user is entering planetmike.com or www.planetmike.com. Just now, I ran across two sites that don’t come up at all if you leave off the www. That feels like a waste of effort or laziness on their parts. Set the server to alias www to the regular site (or vice versa).
You are completely right, and even a catch-all subdomains would be a good idea (for any subdomains that doesn’t already exist).