choosing a rug  

Berber
.. this is an example of the Berber rug I mean:
PS: First picture = from mr. Aalto's villa,
PPS: Both pictures taken from the website below, worth a little sneak peak :o)
http://blog.ounodesign.com/tag/carpet/

Further rug Inspiration
Alternatively, if you are after some more rug inspiration, try the remodelista site, and type 1. "rug" / 2. "carpet" in the search box top right (in the green header).
It should generate pictures of carpets in situ, with some info on them. Good for seeing what you like (or hate !) in a carpet. Enjoy !
http://www.remodelista.com/index.php?s=carpet&searchbutton=Go%21

I like crate & barrel
I purchased a few rugs from Crate & Barrel that have been recently discontinued and nicely discounted. You might consider having a peek at their website.
I choose a couple of solid color 100 percent wool rugs in vibrant colors that I really like; as well as, a few cotton rugs in multi colors to pop a space or warm a tile floor in the winter.
I really like a few of Angela Adams designs too.
While I found the process a chore it was worth the time for me to see, touch and shop many stores before committing to a design.
My difficulty was justifying the expense of the designs I wanted verses what I could afford. A good sale helped to sway my choice.

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My sister used to work for a carpet retailer, supplying pretty high end thick New Zealand wool for hotel lobbies and the like. Perhaps its not quite what you hand in mind but often there are remnants of a good size that you can get cheaply, some beautiful colours too, moss green, cherry red.
There is an edging technique that is really fine and sort of undertucked and barely visible. You can see it on the samples in most carpet shops.
http://www.fernmark.com/