I've considered this over the last six months and more, though not in the military detail you have probably done.

My conclusion was, and is: military invasion of Iran is almost completely non-viable given present situation in Iraq and Afghanistan. It would be an open invitation to escalate insurgency in those countries. It also has almost no benefits - Iranian oil doesn't supply US at all. It would have political repercussions: Chavez might cut oil supply to US. It might lead to impeachment of president. It might encourage a revolution in Saudi Arabia. It would increase instability and violence in Israel / Palestine. It would further isolate the USA.

What might be the benefits? I hope they don't include access to several million bpd oil production, that assumption would be very silly.

It would be insane from just about all perspectives to invade Iran.

Exactly.  As Scott Ritter said this week, "There is no ligitimate reason to ask Iran to give up their stated nuclear objectives."  Its US politics.  

Iran will be delt with using international sanctions, probably for the next 50 years.

But then sanctions may be all it takes for Iran to shut off the spigots - they've already said as much (I'm sure you guys heard the "hurt and pain" comment that one Iranian ambassdor made - that gave me chills). As such, sanctions may be a complete non-starter at the UN as well.