Guerrilla for me was a close second to Hardened on COD MW2. It's pretty easy as long as you know the level. I did the guerrilla ones after beating the game the first time so I went through them pretty fast(maybe 4 hours)
Also, the Iron Man cheeves are pretty easy tbh. Just take your time, don't rush in there guns blazing.
60,000[6/6/11] Shipyard Infiltration - The Bourne Conspiracy