I'm surprised no one mentioned any experience with Wrapsol. They looked like a nice Zagg alternative. They claim to protect the phone from falling impact without that rubbery urethane feel.
In terms of gorilla glass being impervious, there are all sorts of videos on youtube that give you a pretty good idea. Yes, it's a very hard surface and does fine against things like car keys, but those aren't the most dangerous thing out there to the glass of your phone - sand is much harder than steel. I got so paranoid I kept my phone in a little zip-sealed sandwich baggy until the protectors came in the mail.
In terms of drop safety for the bare glass, it seems like you can get away with a 3 foot drop, even onto concrete, with limited damage. Your mileage may vary. I saw one tester do 3 3-foot drops in a row, and the third obliterated the glass. A six foot drop seems to do in the material pretty much instantly.
If my retailer didn't try to squeeze me $7 over list price for a screen protector, I probably would have gone with the Zagg invisible shield they suggested. They do an expert job of installing them, and in retrospect, I probably would have been willing to pay them extra to do it. However, I felt like it was a rip and plunged headfirst into figuring out how these screen guards vary. I will say that that Zagg was the best option I found for a printed custom back cover for my phone for $20 (an option I didn't elect to pursue).
I decided I couldn't go wrong with the Stealthguard deal, They seem to use the same materials as the Zagg product and feel the same against the skin. They're cheap enough, I wish I bought myself two. They do a fine job of protecting the back of the phone (but not the sides or buttons). However, I am a very poor screen installer. I got all kinds of bubbles on my first application, so I peeled it up and reapplied in each region. The end result was a smooth surface, with weird little silvery veins going through where I stretched the adhesive. They left no residue behind, a key factor for me. They also "healed" a little over a few days, but I'm glad I didn't put that on the front of my phone.
For the front glass of my phone I went with the Realook. I was totally naive in my application. I ran the shower on hot for several minutes to get rid of any dust that might be in the air, turned on the heat lamp in the bathroom, put on some nitrile gloves, and laid out a towel on the counter to give me a clean working surface. What a horrible experience! The screen protector was cut perfectly to the phone, but peeled backwards in my opinion with the speaker notch at the end instead of the beginning. And that perfect cut makes the install very touchy, even a degree off and I got an air bubble on the side of the screen. The screen itself adheres perfectly, almost vaccuumed itself to the surface of the phone - but even the slightest bit of dust would show as a bubble. In any case, my towel was full of lint and the gloves just picked it up and spread it around. I highly recommend avoiding both towels and gloves! Clean hands works best. Anyway, before I knew it I had used both screens and effectively wasted them.
This was where the best feature of the Reallook screens comes in, and why I'll probably put them on every device I have the future. The things clean up under warm water! So after peeling the screen up with a toothpick, I rinsed it and dried it carefully with a hair dryer. Reapplied and it looked pretty good, I'm a total spaz so I never got it perfect, but that was never the product's fault. The material is invisible, smooth with the Swype keyboard, and is indiscernible from an uncovered screen. It does pick up fingerprints somewhat, but doesn't everything? It wipes down easily. My only complaint about it is the product listing said it would come with an extra protector for the camera, and it did not. Inevitably, anything over a lens reduces its optical clarity, so they must have stopped doing that. It's perfectly clear, it's smooth, and it can be reapplied. I can't ask anything more of a screen protector. My $11 was well spent, and an extra $3 covered the back. So that's my experience.