Which harnessed seat is tallest?

[EzzysMom]

I'm going to need to buy a new seat for DD1 (age 3.5 now) as DD2 outgrows her car seat and needs DD1's radian. DD1 is in a radian now rear-facing but not far from outgrowing the radian rear-facing. I want to buy DD1 her last car seat, a harnessed that converts into a booster. My kids are tall and thin, what are my best options?

I value ease of operation and install over price concerns.

We have a 2005 Matrix, would love to install the new seat in the center (next to a radian) and get a back seat free for an adult to sit in.

[chickabiddy]

Britax Frontier85 has the tallest harness and converts into a good booster.

Graco Nautilus is shorter than the Frontier but still tall enough to get the vast majority of kids (like not the 50" 70# 3yo I dealt with, but really, most kids) to a safe booster size/age and it is also a decent booster.

[MacKinnon]

I'm not confident you'll be able to free up room in the back of a Matrix for adult with either a Frontier or a Nautilus. They're both pretty big seats! They're both good seats too. IMO the Nautilus is an easier install. It is a few inches shorter, but will last most kids as a harness a good long time. And it converts to both a high back and backless booster. The Frontier is a bear to wrestle with, but will last you longer.

[Mom2M]

I love our Nautilus. It's easy to install, we move it to different cars occasionally, it's very comfortable according to DD and has a pretty high back. DD is a little above average in height, average in weight and has lots of room left. She's 6 years old and ready to change to the high back booster mode but I just haven't done it yet, she's still harnessed because she hasn't complained about it.
The base is pretty wide, though, plus it has a cup holder at arm rest height sticking out on the right side. It is installed in the center of our Hyundai next to a Marathon and just fits, not leaving much room at all for an adult next to it unless they are pretty small!

[DaughterOfKali]

The child height limit on the Nautilus is only 52".

[EzzysMom]

OP here. Thanks for your thoughts everyone. I realized I could also buy my mom the new car seat (frontier or nautilus), snag the radian from her car and put it in the middle forward facing for a while anyway (at least until we have to play bump the car seat again when DD2 outgrows the scenera rear facing in my moms car and needs the radian to stay rear facing) and that might give us room to fit someone in the back seat.

Do two radians one forward and one rear fit well next to each other?

What about a frontier or nautilus with a rear facing scenera?

[chickabiddy]

Originally Posted by EzzysMom 
Do two radians one forward and one rear fit well next to each other?

Yes, wonderfully.