I am surprised that you say the choice is limited - Have you checked in the themes database? There are over 20 Mdl2 themes in there not counting the ones that are shipped as part of the moodle core package anyway. And that's without doing a general internet search to find any others that I know are out there from various sources, but which are on different licences so are not released into the community database.
This particular theme is not available in the community, as has been discussed on occasion before. I believe the idea was not to release this particular theme in order to maintain some kind of individuality for the moodle.org site itself, rather than having an array of other sites using exactly the same theme.
There are many themes around with full width rather than fixed width pages, and the majority of them use a standard font size, which on all my PCs/laptops at least shows up exactly the same size as this one. I know that just about every theme I have put in the community is full width and that one of the most popular recent themes - Mary's Aardvark-Postit theme is a full width variation of Shaun's original Aardvark. And many of the themes are highly customisable in themselves with a settings page that can range from changing the logo, through to my own flexi_ii which has (too) many options for customising, or the many themes which have a custom css tool on their settings page which basically allows you to add/alter any css you want to.
The best option if you can't find a theme to completely suit your needs is to choose one closest to the general look you want and then start to customise it yourself - there are plenty of people on the forum who are only to willing to help with support and advice.