Using envelope case sometimes..looks so corporate when attending a meeting
When i on a vacation i will use my otterbox case..super solid n good for journey n travel..
I personally use Original Playbook Premium Leather Sleeve. I like it a lot and it doesn't add too much girth or weight to the thing. I just gently pull it out from the center and have no problems with warping/stretching that you mentioned. Simple and elegant... that is unless you need extra slots etc (if that's the case then I suggest Journal Case)