My son is 2+ and my daughter is 6 months. She is too long for her infant car seat. I was hoping to move her into my son's Roundabout and buy a new seat for him. Was thinking either the Britax Regent (

[tdenlow]

[Joolsplus2]

At only two, I'd get the Marathon or Fisher Price Safe Voyage Deluxe or Graco Safeseat2 (if he's a long way from 40 pounds and you don't need the higher weight limit). I think the Regent is too big, maybe that can be your *next* seat :)
Julie CPS Tech and mom to 3 in seats
http://www.cpsafety.com/articles/RFAlbum/SarahMA.aspx

[tdenlow]

What about the Radian from Sunshine Kids. My son is close to 30lbs, and 36 inches. I was trying to eliminate buying seat after seat?

[Joolsplus2]

That's a great choice, too, as long as it fits in your car. The objective is to keep a kid harnessed to at least age 5 (I think any of the choices I mentioned at first are good for that), and then in a booster till around age 10. But some of us like to keep our kids harnessed longer than age 5, so the Regent keeps them harnessed till age 8-11, depending on how big they are. Since you can hand things down, and seats all expire after 6 years anyway (7 for the Radian), you're still kind of at the beginning of your seat buying career (like shoes and bikes, you just have to keep buying the right size for each stage of growth).
Julie CPS Tech and mom to 3 in seats
http://www.cpsafety.com/articles/RFAlbum/SarahMA.aspx