All my iPhones to date, starting with my 3GS, have lived inside a Smart Case from Waterfield Designs; my iPads have likewise lived in one of their Ultimate Sleeve cases. They are a local firm here in San Francisco, and I love their products and their service.
When I pre-ordered my 6, the site I visited next was theirs to get an estimate of when they would have my favourite case ready for the new phone.
But there was no Smart Case listed for the iPhone 6. I reached out to them on Twitter, and it seems it will not be there for a while. They do have a number of other options, but none really appealed to me in the way the Smart Case had (and I have had 3 of them now spanning 5 years of use, so they have become familiar).