First thing I bought was a Spigen screen protector, it was more expensive than most but I knew they made good screen protectors and I wasnt disapointed, only one cut out for speaker and great fit means it is pretty much unooticable.
I then bought an official Google Bumper in grey, it started to discolour around the edges on day 2 so I asked for a refund, it is a nice case but not worth the money and seems only the black colour is useable and I think it ads a little too much bulk given there is tons of other black options, the official case's biggest selling points to me were the colours..shame.
Given Spigen did a good job with the screen protector I thought I would try their Ultra Fit case...it hasnt arrived yet, but it seems to have been reviewed well and looks pretty much like the back of the nexus minus the logo and is thin...hope it works out...although at least this one was only ?7.