I'm a huge fan of the skin+sleeve combination. This way the device is protected against drops (except when I'm using it, I know, but I'm just careful) and also scratches even when in use. I think it is a good compromise, the device is protected but you keep the look & feel of the phone.
I have an iPad 3 with Power Support on the front and Best Skins Ever on the back, and I used to have an iPhone 4S with Power Support on the front and the back. Never liked to use these for the sides, because the feeling of the aluminium is lost.
The iPhone 4(s) was made entirely of glass, so putting on a high quality body protector, glass-like, was enough to protect it without even noticing that it's there. The feeling is exactly the same, the look is exactly the same.
This only applies to the front on the iPhone 5 (I already got a couple of SGP ultra crystal protectors). I've been looking at back protectors, and actually I was thinking about ordering a BSE set, but a few things are pushing me away from back protectors:
-The back is almost entirely made of aluminium, so putting on a skin that is made of a different material (plastic in this case) kind of defeats this.
-Since the back has two different materials and the surface is not smooth, dry installs are NOT an option, since you'll see bubbles and imperfections everywhere. Not a huge fan of wet installs but I think they are a better option this time around.
-Most brands use a 3 piece design for the back. I think we should avoid these, it's hard to get them properly aligned, and they will leave gaps which will grab dust easily in a few weeks.
The second and the third points can by avoided by purchasing something like the BSE back. The first one is something you'll just have to put up with. Since they are so cheap I might get one, but I'm still considering whether to install it or not.
I'm 99% sure I won't install anything on the sides, just like I did with my iPhone 4S for the same reason. Since they come with the back I might take a look anyway.
This is my opinion. I think you'll only be able to fully enjoy the iPhone 5 by installing a screen protector on the front and using a sleeve to carry it around.