Don't forget the cases that protect a device's sides and rear only, leaving the face/screen exposed. I use such a case (the
Zagg Arsenal) for my Samsung Galaxy S4, in combination with the
invisibleSHIELD EXTREME screen protector and a full-enclosure zippered case that also holds earbuds. (I've used such redundant protection for my devices ever since a leather cover and screen protector failed to prevent my Treo 755p's screen from cracking, while in my purse.)
I now use both a cover and a sleeve for my NOOK Tablet, NOOK HD, and laptop. Each NOOK has a BN screen protector and lives in a cover (the leather trifold
Soho for the NT - my fave, unfortunately discontinued - and the faux-leather folio
Lautner Cover with a magnetic closure strap for the HD), and when I take a NOOK on-the-go I slip the entire NOOK/cover ensemble into a
10" M-Edge Touring Sleeve that has a zippered, external accessories pocket. In contrast, I use my laptop bareback, but when on-the-go I slip it into a sleeve, which I then pop into a carrying case that has a shoulder strap or into the protected computer slot of a rolling tote.