Grant has a new convertible car seat, just like a big boy. We went with the Britax Boulevard 70. I think that the "70" has something to do with pounds? I don't know really. I just know that I wanted to be able to adjust the straps without having to re-thread them, and I wanted black so that we could avoid the unavoidable messes that come with having (an eventual) toddler. This seat will go either forward facing or rear facing, and so it looks like Grant has about 3.5 more months of staring at the back window before we'll turn this baby around. Literally.
The seat is much nicer for Grant, because it's larger and offers more air flow than before, keeping him a little cooler than his infant carrier. It also allows him to see more. Sometimes, when we get to our destination and I go to lift him out, I see that he has grabbed something from the backseat that is now within reach, like my purse straps or other bags that are sitting nearby.
Right now, it seems that Grant likes to sleep in it more than anything.