The spray in insulation is the best there is. As a matter of fact, where you are it would definetly be the best route. With this insulation there is no requirement for a wrap. The insulation itself is the wrap. All the wrap is really used for is a moistier barrier. It is used to keep the warm moist are from coming into contact with the cooler are on the other side of the wall, which with any other insulation will occur. Because this insulation is sprayed on as a liquid, there is NO air infiltration past the insulation. It is also the only insulation that maintains the R-value no matter what the conditions are. Fiberglass insulation drops the r-value as the temperature drop. Also, moistier in the insulation will cause reduced r-values.
The down side to this is the price. It will be considerably more money to have it done, and you will probably need some sort of air exchanger. The up side is the engery costs are going to be considerably lower, and they are perpetual (especially the way gas and oil prices are going).
If I were building a new house, I would VERY seriously consider it.
.
