Earlier this year I purchased a 2004 Chevy Colorado from a dealer here in town as my "Plain Jane" everyday truck. (I keep my toy's for the weekends) This truck had been smoked in since it was new. The dealer was having trouble selling it because of the smoke smell. He knocked a grand off his price and had the interior "De-Ionized. (washed with de-ionized water which is supposed to absorb the offensive odor molecules). It did a good enough job that I bought the truck.
However, after about a month the smell started to come back whenever the A/C was blowing. I bought a spray bottle of Febreeze and with the A/C blower on Hi and recirculate, I would spray it into the interior heater air intake under the dash. I did this once or twice a day for 2 weeks and now the smoke smell is gone.
So however you decide to attack this problem, make sure you take care of the heater/ AC ystem as well or the smell will keep coming back.