I am using just a best skins ever on my phone no case, well sometimes a holster but not offen. i really like the naked look of the phone and with the skin on it i don't have to worry about scratches
I have an Invisible Sheild, and I'm pretty happy with it. It's very clean looking and I don't worry about the phone like I would if it was completely naked. I am considering getting a case, but I'm hesitant.
Update, still using the full body skin with just a holster. My bodyguardz is doing a good job, the ends are still down and no bubbles. Wow i think i will be caseless for a long time.
I notice streaks on my screen with the IS, but it's not bad. In fact, I find that it looks better then the naked screen since it resists finger prints. Finger prints look far worse then the slight streaks.
BTW you can always use a skin on the back and pick the screen protector of your choice for the screen.