There are quite a few sellers on Etsy.com that sell sleeves. You might need to contact them to see if they can adjust the dimensions to fit the Smart Cover as well.
Also Beyza has a sleeve For the original iPad Air but I don't know if it will accommodate an iPad Air 2 with Smart Cover. It may well do as the iPad Air 2 is thinner. Again it might be worth while contacting them.
Personally I'm currently using a leather sleeve from Vaja which I originally got for my iPad 3 and have kept. It works just fine with my iPad Air with Smart Cover and although I haven't tried yet should work with the iPad Air 2 with Smart Cover. They don't seem to have anything right now though.
I don't think there are many iPad Air 2 specific sleeves let alone any that also accommodate the Smart Cover. It may be a case of using a sleeve for a previous model as the iPad Air 2 is much thinner and could work with the Smart Cover.
Just got this sleeve over the weekend and it has a great build and very soft protective inside. Can't wait for my iPad to come today so that I can use this.
Just received this one. It fits great, will accommodate a Smart Cover (as pre another poster), the magnet is nice and strong. I've used all sorts of cases and sleeves over the years. I've finally settled on a skin for around the house and a sleeve for travel. The fact that this one turned into a stand means I don't have to carry an additional stand. Great but for the price.
Btw, the stand function is really nice. Just a bit worried if it's too slippery on a plane table. Will find out today.