I will second the comment about a J type fork. I had a touring bike with an aluminum frame and fork and switched all components over to a 2008 Kona Jake the Snake which has a Carbon fork. I thought the Jake was far stiffer in all aspects including the fork. The odd think about eh Aluminum fork I had was that it was very springy and had a good bend to it thus absorbing a lot of shock.

Ultimately, go with front suspension if you want a smooth ride... There was a great rant by bike snob a while back contrasting Carbon with Aluminum. He suggested it was a lot of hype.... Honestly, I really can't tell a big difference. I have 2 bikes with Carbon forks, Bikes without and they feel the same to me. I also have a tandem with front suspension and that certainly gives a smooth ride with it's long wheelbase.