For a first alpine/hardboots board, I wouldn't go below 170, and maybe look at boards up to 175. If you are already good at carving your present gear, you might do well with a freecarve board. Check out the Donek 171fcII or Prior WCR171 (a bit stiffer I think). Otherwise, all-mountain carving boards are a great intro to the sport. Look at the Donek Axis or Prior 4WD.
I assume you mean softboots. Yes, check out a boardercross board like the Volkl Cross (not made anymore, look for used), F2 Speedcross 165 (longest one, sold here)
Donek, Prior, Coiler (I didn't mention Coiler above because they have about a 10 month wait list), F2, Volkl, Nidecker, Hot...