Though CSS can probably offer a cleaner solution, personally, I use jQuery to equalize the height of the widget sidebar with the main content container.
You're already jQuery UI for your datepicker calenders so I can't think of a valid reason to not make further use of jQuery.
I've previously documented the necessary code here: http://thematictheme.com/forums/topic/equal-height-for-widget-column-and-container-column/#post-2000
The code is added to functions.php.
Note that in the provided example, #primary refers to the sidebar and #container refers to whatever your main content container is called. Change these ids to match your own code.
Also note that I've wrapped the jQuery in conditional tags to limit the equalization to specific pages (mainly those where the sidebar is present). Since all your pages have a sidebar, you can probably delete that aspect of code...
...delete these lines:
// Use WordPress conditional tags to target specific blog pages onyly...
if(is_home() || is_single() || is_archive() || is_search() ){
...and this line:
} // end if is_home