Opinions on car seat options.

When my first was born we got a infant car seat. The kind with the detachable base that you can carry in and out of the car. When he got to big for it we moved him to a Graco 4Ever convertible car seat. It goes from rear facing 5 lbs newborn to over 100 lbs backless booster seat.

My question is, should I use the infant carry seat with this new baby or just go straight to a Graco 4Ever seat?

Keep in mind I will also be lugging around a just turned 2 year old.

Anyone have any experience? Opinions? Thanks!