We are taking a trip in the fall, and didn't want to pay for an extra seat on the plane. I also didn't feel comfortable checking a car seat, not knowing how banged up it could get.

My parents are driving to the destination, and can take the car seat. But we still need a seat to take him to the airport in. I was thinking of purchasing a convertible car seat, as it can be used longer than the infant one he has now.

He will be 5 months, assuming a convertible car seat will be fine? Anything I should look for specifically? Any features that are a must?