hey man...anything between 170 and 180s should be fine. You also need to consider what u weigh...if your like 220, you need to be on something like 185's, but if your of normal build stay within the 170-180 range. Also, pay attention to how much flex is in the ski...a stiffer ski is less forgiving in the park, but generally better on the groomers.
Finally, the width of the ski is important depending on what type of snow your going to be riding. Lots of snow get a mid-fat...little snow get something like 1080's, etc