Exterior Walls Advice: 2x4 or 2x6
I live in the North Houston Texas area. I am trying to determine whether there are any benefits to going with 2x6 exterior walls versus 2x4's. I am also trying to determine what is the most cost effect insulation: foam vs blown in cellulose. I've heard that using an expanding foam, although it increases "R" efficency, also requires an increased cost for HVAC requirements and costs.
I would appreciate your opinions and information as to why you would select one over the other.