Hi Ceclilia.
What did you go for? We just got our Vanity URL invite and I have accepted what Google was offering. It is a bit frustrating that we did not have the option to alter the vanity URL to simply Binarydrive, without the CoUK at the end (especially as we do own the .com) ... either way, it is far more attractive, and memorable, than the old numeric string.
Regardng your question, I agree with Kane, go for BRAND over keywords / location etc. I think over the next 12 months we will see even more penalties for location / keyword spammed URL's .... it really frustrates me to see poorly consrtucted websites ranking at the top when you search for "engine tuners in Norfolk" and get a top listing of "enginetunersinnorfolk.co.uk" or SIMILAR !! Build your brand.. think big.. one day you might want to be National or even Global
Tristan Haskins