How would you go making a calendar without using tables? A calendar is a tabular data holder.
Floating stuff around would probably be a nightmare.
If you have proof of concept, we would be happy to look at it. We have a bug tracker on http://tracker.wp-eventscalendar.com/my_view_page.php where you can propose a feature and maybe provide an example?
As for you remark about the HTML, I hear you. In fact, since I'm the new guy in town on this plugin, I have lots of ideas to improve the plugin. I am thinking about getting the HTML, CSS and JS out of the PHP code. Or, at the very least, the CSS and JS stuff. And for the HTML, I was thinking about maybe a class that would do the job, like a ec_html->div(array('class'='mine', 'id'='yours', etc.)) and stuff like that.
Evidently, I'm not alone and democracy is the rule. So the team must agree.
So please stay tuned. As a (new) team (please see http://wordpress.org/support/topic/292773?replies=2 for a bit of an explanation), we are evolving and working hard to make it work for you folks.
Thank you for you patience,