There really isn’t any reason to add a rowspan to your table. You can achieve the [same thing](http://jsfiddle.net/6WE6E/) with one row.
High season: 01 Nov – 20 Dec & 07 Jan – 30 April
Christmas: 21 Dec – 6 Jan (min. 3 nights)
And because I noticed you were using cufon for the header font, I thought I should mention there are better alternatives.
* [Google Web Fonts](http://www.google.com/webfonts) – for predefined fonts
* CSS @Font-face – for custom fonts, check out [fontspring](http://www.fontspring.com/blog/the-new-bulletproof-font-face-syntax) and/or [fontsquirrel](http://www.fontsquirrel.com/fontface/generator)