i know everyone on here is like "o yeah go longer,your a pussy if you dont!"  but just go with what your comfortable with. just try some different lengths and see what you like most. dont listen to all the people all here saying b.s.  go with what you like and what you can ride comfortably.  p.s. in my opinion your weight is more important to ski length than height because the longer ski provides more surface area, but why would a guy whose 6' 150lbs need a ton more surface area to float that a guy whose 5' 8" 150lbs?  they would both sink equally in powder because they have the same weight.  i could see why the taller guy might need a little longer ski for park for more stability because its just geometry and the physics of it all, but from personal experience i have had no harder time stomping landings on a 172 than a 180.  in fact it was easier because i could control myself  in the air better, expecially on spins.
thats my input, ill probably get shit for it, but i stand by it any way. if it was confusing i will try and clarify