We have the Britax (Roundabout) car seat for our little girl. It is probably one of the most expensive car seats out there but it is worth every penny and more, it is WONDERFUL!!!! My husband and I bought one for our car, one for grandma's car, and now with our second little girl just born, we are looking forward to buying another for her when she grows out of her infant seat.
The Bristax roundabout is SO awesome, it can rear face and hold an infant right up to a toddler until they are totally out of a car seat. My husband is 6'6" and so both of our girls are very long. Our oldest grew out of her infant seat at 5 months old, so we bought the Roundabout and put it rear facing in our car. She is now 2 1/2 years old and 30 lb.'s and still fits perfect and cozy in the seat.
I HIGHLY recommend this seat! Check it out :-)