Hey trusty lemon,
I did a little research and this is what I came across and found:
"What we used to do after all the burned stuff was stripped from the house was to completely air out the house with fans and then encapsulate the odor with a strong primer like Kilz, Zinsser Bullseye or white shellac prior to topcoat. We even sealed the subfloor under the carpets and joists in attics and floors if they were smoke stained and smelled. That always seemed to work. You may have skipped that step. Just painting drywall with latex wall paint won’t do the trick if the problem is bad." This is according to the Capital Gazette. Sounds a bit extreme, but it is an option.
Others recommended something like Odoban. I've used that before on some clothes and pet stains and it's seemed to work, but it has a bit of a strange smell itself. Another chemical option I found on amazon is ZUSOE16 Smoke Eliminator Professional Strength.
The simplest option may be to just open windows and wait a while and see if the smell lessens. Some folks use baking soda in there refrigerators to help keep weird smells trapped. You might experiment with that on the furniture. Dust some on, wait a day, and vacuum it off. Bowls of vinegar are worth trying too, supposedly they wick the smell away. Good luck!