J.S.
I am a Child Passenger Safety Technician
Do not buy any of the 3-in-1s under the name Safety First, Cosco, Alpha Omega, Enspira, Eddie Bauer, etc. They are exceptionally awful seats. They have serious installation issues, straps that tend to twist, ridiculously low top harness position, a 40 pound harness limit and they make the worst boosters on the market.
Avoid the Britax Diplomat and Roundabout. They have short shells and will not last you for very long. The Marathon and Boulevard are both great choices. They rear face to 35, forward face to 65.
The Evenflo Triumph Advance (NOT the original Triumph) is also a great seat. Rear faces to 35, forward faces to 50.
The Sunshine Kids Radian 65/80 are wonderful, narrow seats, esepcially great if you need to install car seats next to each other. You will have no trouble fitting one in an Altima.
Ignore the advice telling you that you can't fit a large Britax rear facing in a car. This is quite incorrect. They will fit rear facing in the smallest of compact cars.