But what about everything else FS?  The geography, the population, the resisitance to Regime Change?  I personally think Iran would be far harder than Iraq and we've been Iraq for years already.  The War would be the easy bit, no arguements there.  But what about winning the peace?

Iran and Turkey are two huge countries with numerous population of the same order.
However Turkey population and biggest towns are concentrated on coast.Moreover it is a US equiped army and its equipement, at least its air power, can be neutralized easily by USA since they have provided it.And without aviation their army is dead as a classical army.

Iran of course, has its own equipment now for 90%.And their army is already taylored for an asymetric fight with USA with huge numbers and a huge missile inventory.They have already assumed they will not have air superiority, and they have a denial air power strategy.

Iran is difficult to invade from the Gulf due to mountains and south is desert

Its main population and centers are closer to Caspian sea and in some wooden and moutaineous areas.

To bomb it is not so obvious without a local country, since it implies to use aircraft carriers, and they have to be likely in arabian sea since they can trap you in the Gulf by closing Ormuz (mines etc.).So far aways from main populated areas and centers.Almost 1000 miles from Teheran to south coast.

If you use bombers without a local country they have to come from Diego garcia and it is a long path.

Contrary to Turkey which has numerous islands in front of its coast what you can invide and where you can deploy depots, air bases etc..

And Iran strategy was to impeach USA to get allies ready to support USA for a preemptive invasion like for Irak, by deploying thousands of ballistic missiles, short and longer range, and threatening to attack their oil installations and close the gulf (plus using local shiite in other countries to destabilize those countries).

Without some local ally, Iran is much more difficult to invade.

Iran defense strategy is close to North Korea even Iran has better equipement and much more ressources.

I think that Iran is by far the most difficult country to invade in the area and first for geographical reasons then preparation and commitment (suicide combattants like Japan in WW2).Then Israel due to its quality army but without strategic depth.

PS:Considering Egypt their military while better than in state Gulf, is not very commited and professional.