Wow ... a big project for someone new to PHP and MySQL.
Yes, Drupal and Joomla would be good for your application.
There are hundreds of plug-ins, and modules available for various
user profiles, updating stuff, etc.
I see one problem with your idea ...
The businesses in your area won't have the time to keep going to your site
and editing the accomodations of their businesses ... especially hotels or motels.
You'll discover that your site will never have current (or valid) information.
That means, you'll be doing all of the site updates, and that won't last very long.
You could just have a local business directory, with info, photos, links, etc.
If you are lucky, your town has "Free City-Wide WiFi" ... that means, you can provide info
to any tourists with iPods, laptops, and WiFi PDA's. That would be something that
your local businesses would be interested in. Someone driving into town could pull-over
and instantly find everything they need about your town's businesses, along with some
simple Google maps.
Without the details of dates and accomodations, you could program this with very
simple PHP/MySQL, and the site upkeep will not be too time consuming. You would not
need Drupal or Joomla, just a simple, easy to use website.
Your site could become the "Visitor's Information Center" online.