What length?

if you get a twin tip you would want to add at least 5-10 cm, and if you plan on mounting center add at least 10 more, so a 181 would probably be good at recommended but otherwise look for more like 187+

^Wow - no way.

First, what's your skier ability?  It sounds as though you're a relatively big guy, but this is your first set of twins.  I'd normally say for someone your size 176 is a bit small, but hey, if that's your preference, than fine.  I'd say that the 181 Hazmat should be fine for you as it is a semi-wide ski and the double rise shouldn't make that much of a difference.  If you're uber uber advanced and were riding 176s for kicks, maybe then you could go as high as ^this, but I think you'll be fine at 181.  I'm 6'0 ft and 185 lbs and I ride 185 Scratch BC and 180 Salomon SPK and they're both fine.

So yeah, skier ability will help, but overall you should be fine with 180.

i would consider myself advanced, not expert.  can ski anything but some stuff might not be pretty. i spend most my time in the trees, bumbs, steeps  and will get into the park some. don't want to get the 181 and then soon want longer... but i can get the 181 for cheaper which is why im leaning towards it.

if your not gonna be throwing down off big kickers but still like jumping 181 should be fine alot is preference