I have a 2g myself. My buddy stopped by with the new 4G and the speed was amazingly faster.
When I started my search, I compared the 2g, 3g and 3gs. I wasn't impressed with the 3gs speed at all and saw little difference between the 2g and 3g so I went with the cheapest, 2g.
With re-sale, I bought a 2g from a buddy for $25 and gave it to my wife. She had it 2 days and killed the screen glass. Bought another on Craiglist for $100 in mint condition.
I listed the broken one on craigslist for $100. Had someone call me and asked if I would deliver it for $150! I was like of course! 20 minute driver later I had $150 in my hand!
I asked why he said all the iphones on craigslist he called on kept getting sold. I was like okay. He smelled of marijuana though so who knows.