Re: Car Seat Dilemma: WWYD? (with 2 dc or more)
We have a Roundabout - we used it since birth for DS. We love it. It is great rear facing and foward facing. I would really really recommend it. You YDD can use it and it can be used by the next babe.
For ODD - I would NOT go with anything that didn't have a 5 pt harness. At 2.5 - she is just too young for the booster style seats. It wouldn't be safe enough. You can get a Marathon though. They go from birth to atleast 60lbs (I am thinking it may actually have been 80lbs but that sounds crazy.) It is bigger, but that is mainly only a factor for rear facing. We would have gotten it for DS, but it wouldn't fit rear facing in our cars and we don't like the carrier style carseats - just not safe enough for me. Anyways, it isn't that much bigger than the Roundabout when they are both foward facing. That would take your DD up till she is really ready for the booster style seat.
Personally - if I were you this is what I would do- if you plan to turn YDD around when put into the new carseat, I would get Marathons for both of them. BUt rearfacing as long as possible is much safer so I would personally get the roundabout and keep YDD rear facing and get a Marathon for ODD.
Other carseats may have smaller bases and fit better *if* there are three in your car - but IMO you only have two kids now, and those two kids should be as safe as you can possibly make them - which means a Britax - there is not a safer carseat on the market than Britax. It meets European safety standards - which far surpass US standards.