Greetings Walt.
I'm also a big fan of benchtop router tables. A good size seems to be about 18x24". This is less of an issue if you make your own fence. I have a couple of commercially available fences designed for benchtop tables and 24" is a good width for these.
As far as plans... there are billions out there on the web. I'll post a few. A good strategy is to use mdf for the table; if you glue up two pieces of 3/4" stock you'll get a very nice table. My local Home Depot has 2x4' sheets of mdf for $6. This would be more than enough for a table.
Most folks like to cover the table top and bottom with formica or other laminate. For my next table I intend to use hardboard masonite) for the top.
If you do a search on these forums you'll find lots of great user's router tables.
http://www.rd.com/americanwoodworker...&contentId=628 http://www.woodsmith.com/issues/156/...-router-table/ http://www.rexmill.com/ (in "projects" section)
This is a good plan available for purchase but you should be able to find some good freebies:
http://plansnow.com/dn3062.html
Have fun,
Michael