Re: Smell from vents when AC is off.
Okay, reporting back. All traces of smell are gone. Of the two things I did (cabin air filter and vent spray), the vent spray provided 99% of the odor resolution. Importantly though, I feel still feel like getting the cabin air filter is important for health reasons...
Process (the spray can has good instructions and I followed them. I'll still describe what I did because I also installed the filter at the same time):
(If you're not going to install the filter, you can skip step 1 because you don't need to remove the panel)
1 - Open hood and remove the plastic panel covering the cabin air opening. It is located just below the passenger side windshield wiper. (WK_Jeeps and the instructions said to remove the wiper, but I didn't because reinstalling the wiper requires a torque wrench, which I don't have and I didn't want to mess with that. Even with the wiper attached, I was able to move the panel enough to get all the access I needed). [EDIT: forgot to mention that you have to pull back some rubber stripping from left to right to be bale to move the panel]. One point about WK_Jeeps...the instructions for the cabin air filter appear to be more relevant for a WJ, not WK...
2 - With the vehicle running and AC on max fan speed with fresh air (not recirculate), spray one half of the bottle into the opening for the cabin air you just accessed. (note: if you aren't installing the air filter, you can just spray through some of the openings on the panel under the wiper. You'll see light coming through from the cabin) You might want to use the straw nozzle for better control here if you didn't take off the windshield wiper...I did.
3 - Get in the car, turn off the AC fan. Attach nozzle, and spray even amounts of spray into the four dash vents, two rear passenger vents behind console, and two floor vents in front foot wells near center stack. (Keep a paper towel handy to wipe any thing that drips out, especially from the floor vents. Make sure to get the nozzle way back in each vent to minimize leaking and maximize coverage).
(If you are planning to install the Cabin Air Filter, I'd do it here. It comes with very simple instructions and is very easy to install. You remove the plastic cover blocking the air opening which you just yank out. You'll throw it away so don't worry about being too gentle. Align the new bracket and secure with included plastic bolt things. Place the filter in the bracket. Place the cover on the filter and snap into place. Done.)
4 - Drop your windows, turn AC fan to max fresh air (not recirculated), and run like this for 10-15 min.
The spray gave the car a fresh and "woodsy" smell that lasted about a day or so. Now, it smells like nothing. That, or I have gotten used to it.
The spray works.