To be honest, I think 300C is a great choice, especially if you still have 1 performance car in the family.
May not be a great performance car, but performance and handling will be the last thing on your mind when transporting your precious baby around.
When our baby was born I drove so mildly I reckon I would have got flat cornering with zero body roll even if driving a Citroen 2CV
Even now she is 1yr old I do my utmost to stay in the slow lane, sometimes driving extra slow so journey takes longer and she sleeps longer in the back.
Actually, come to think of it HOW ABOUT A 2CV
I bet that's thrown a spanner in the works now