Secondly, the combat mission ending date in Iraq set by GW could have easily been renegotiated and extended and many people believed Mccain would do just that if he felt Iraq wasn't stablized yet. Also, he was very clear about his aggressive stance toward Iran. If he would have taken office we might be in three wars right now rather than one.
As for Obama's troop surge and his previous quote, personally I believe Obama was trying to make the pro-war guys happy, trying to play the middle line. "We will increase troops now but get out in two years", it was an obvious compromise.