> Also, I'd be surprised to see more than a dozen AP's in a typical suburban location, so while 2.4GHz may be congested in general, by the pigeon-hole principle, you can probably find an empty channel.
There will be at least some overlap if you have more than three access points in range. There may be eleven "channels", but at best only three of them (1, 6, and 11) are completely disjoint. Worse, access points too weak to properly detect can still cause interference. You may only be able to _list_ a dozen APs with at least marginal reception, but there can still be others close enough to cause problems.
MIMO and beam-forming can help immensely in cutting down on the interference, but you won't find those features in bargain-basement 802.11g routers.