I will hopefully be building before Summer is out.  I am in coastal Alabama, a very hot, humid climate and in a hurricane zone.  The wind code for my location is 130 MPH. 

I will be building stick, probably 2x6, with brick veneer.  SIP and ICF are definitely out.  I will be using at least one inch of closed cell foam between the brick and the sheathing in place of house wrap.  There will be a one inch ventilation gap between foam and the brick.

If it is possible, I would like to use 2+" of closed cell inside the stud bays.  I am familiar with the "drying to the inside" problems with closed cell in walls in this environment.  However, how is this arrangement any different than a SIP wall?  The outer skin of a SIP wall has no ability to dry to the inside, so, at least based on my unprofessional and inexperienced observation, a SIP wall with housewrap and a stud wall with closed cell/housewrap should have about the same inward drying ability as far as the sheathing goes, but I would think that the studs in a stud wall would have more opportunity to dry towards the inside than the splines in a SIP wall.

Now, as for my proposed assembly, 1" CC + sheathing (prob. OSB) + 2" CC, the exterior closed cell is less permeable than housewrap, so it may slow down outward drying too much to do this with CC in the cavities.  On the other hand, it would seem like it would make a much better barrier to bulk water intrusion than housewrap.

Of course, plan B is closed cell exterior, open cell in cavities, but I'd really like to get the structural advantages of closed cell in the wall cavities if I can, and I'd also like to have only 2" of insulation in the cavities and plenty of room for pipe and wire without upsetting the insulation.

Another possibility is 2x4 framing with 2+ inches of closed cell all outside the sheathing, interior cavities empty.  I don't know if that will meet the structural requirements of my design at this point.

I am aware of the cost advantages of cellulose and fiberglass.  If I need additional R (which I will determine when we run an AC load calc) I will consider those options.  22 years ago when I did load calcs in college, it was obvious that for this environment solar gains and air infiltration were larger contributors to air conditioning loads than the R value of the walls. 

If anyone would like to comment I would appreciate it.

What did you end up doing?

Still waiting to build, actually, but I have decided to go with open cell foam in the stud bays only, mostly because on the hottest day of the year (our overwhelming concern down here), I can't see that there's more than about 1500 BTU's per hour at peak temps to save with a foam over OSB approach on the walls in this climate zone in the Summer.  I gather that the Building Science people concluded the same thing because they do not recommend insulated sheathing in this climate zone.

After actually seeing the amount of steel bracing the builders are using in response to the 2012 codes, the structural benefits of closed cell foam just didn't seem as appealing as it once did.  The philosophy down here is steel fasteners/brackets on every framing member along every load patch that leads to anchor bolts into the footings.

Similarly in the attic, once the framing members are covered with about R3.5, the first additional inch of insulation (past about R24 ish, 2x6 rafters) is generally only going to save about 1500 BTU's an hour or so at peak Summer loads (based on the size of my attic), and each additional inch will save less.  There really isn't much justification for going super high R in the attic down here, but there is plenty of justification for an approach that insulates over the framing members in the attic, so that's what I will do, plus I'll add a fudge factor, a little extra even though my calculations indicate it doesn't save much, just to be sure.

At the coldest Winter conditions, the heat loss through the walls is a little more significant, but we only have 1667 heating degree days here, and I wonder if you build a really tight house here if you really even need a heater beyond one or two space heaters. 

This is based on a very simplistic conduction heat transfer only calculation.  There are additional loads due to solar radiation on the brick and through the windows, but I've got a lot of shading.  Also I haven't calculated any latent loads, and I'm not going to, I'm going to leave that to the professionals (and I will adjust my insulation plan based on the room by room loads), but a fairly simple analysis indicates that foam outside the sheathing here won't buy you much, and it will require builders and subs to do a lot of detailing on the water management issues with materials and methods they are completely unfamiliar with.  We have a massive, and I mean massive, amount of wind driven rain here, and it's 80% RH here 80% of the time, and I have rarely seen a house with issues.  So, long story short, I am going the extra mile, but I am simply going to maximize what I can do within the boundaries of what my builder is comfortable with, and I think it will work out well.  Instead of spending an extra $2000+ on foam over the OSB, I will maximize other components, such as mechanical systems, and manage radiant and latent loads

And, for those who talk about the cost of spray foam, with the prices I've been quoted and the budget I've got, it's just not that much more money for my house.  Ventilated attics are pure misery down here in the Summer.  Others have differing opinions and many of them are valid....

What type of insulation do you plan to use in the attic?

The present plan is to use open cell spray foam at the roof line and spray to R30.  It's a story and a half with some AC equipment in the attic so I want the entire roof deck insulated.