FWIW, I went thru a similar thought process when found out we were going to have a baby. At the time, we only had the Boxster as a fun weekend car (since we lived in NYC, and didn't really need a car during the week). After baby came along, thought about selling the Box, but I loved the car, and also made so many friends in the tri-state area from Porsche car club events that I just couldn't bring myself to sell the car.
We ended up getting an 08 Audi A4 Quattro Sedan, which has served well as a family truckster, and I drive my Boxster to work everyday now (now work and live in NJ). If, for any reason, I need to take our 8 month old baby boy somewhere, I can put our little guy in his baby seat in my Boxster. If all 3 of us need to go out, we take the Audi. No problemo. ....and I get to still have fun in the Box!
Our boy loves rides in the Boxster!