Like I said it depends on the persons perspective. If you don't mind having to go through all the hassle of selling ur phone then do it. but like you said, you rather turn it in than going through the whole process of selling it, so you choose convenience over money, which is perfectly fine because that works for you.
In my case, I don't really mind having to sell it and making some bucks. I have sold a lot of things on craigslist and I've never had an issue. I never share my Phone number, I meet in a public place (such as the food court at a mall) they give me my cash, I give them the phone, deal's done, no biggie. I'm actually trying to decide if I want to sell it now or after the new one is released. mmm decisions.