6 years did go fast. I have all the phones too. I normally pass them down for 1 year, and then I get them back as I pass on another one.
I always use 2 generations ago as an iPod.
I like the 4/4S too. The design was remarkable with the all glass, plus retina, all in the same year.
Nevertheless, I really liked the first generation iPhone too!
Still, the 5 is great feature-wise.
3G and 3GS were not my favorites, but hey they did work quite well and the 3GS gave us the tap to focus camera, which was a nice little step up. I hate the little cracks that would form around weak spots in the plastic though.