Which Kindle would you recommend?

I’m seriously thinking of getting a Kindle e-reader. I will more than likely get the least expensive model simply because I work at home and have access to my PC all the time.

My basic question is whether to get the one Amazon sells “with special offers” or the one “without special offers.” I’m not to sure about the difference between these two. Does the “one with special offers” display advertisements when I’m reading? I would not want that, but I doubt I would mind if it displayed advertisements when I wasn’t reading.

I’m open to considering the more expensive models, too.

What has your experience been with your Kindle? What model do you have?