I'd stick to the 24 mg liquid. 36 is the highest recommended strength, and although your wife smoked non-filters, she only smoked one pack/day. It's too bad they won't let you select different nic levels. It would have been nice to get some in 18, 24, and even 36. Some folks like to use something very strong for cravings or special times of the day, first vape, after eating, etc.
Vapor is not the same as smoke, and a fair number of people find it very harsh, hard to inhale without coughing, at first. The higher the nic level, the harsher it will be. vaping technique (lots of threads on how to do it differently than smoking), PG/VG ratio, and nic levels can help with the harshness, but it can take a little while to get used to the new substances. Don't let your wife get discouraged. One of the great things about ecigs is they mix well with regular smoking, unlike the patch or gum. If she has trouble quitting at first, the ecig will gradually replace the regular smoking, not be in addition to it.
Vapor is not the same as smoke, and a fair number of people find it very harsh, hard to inhale without coughing, at first. The higher the nic level, the harsher it will be. vaping technique (lots of threads on how to do it differently than smoking), PG/VG ratio, and nic levels can help with the harshness, but it can take a little while to get used to the new substances. Don't let your wife get discouraged. One of the great things about ecigs is they mix well with regular smoking, unlike the patch or gum. If she has trouble quitting at first, the ecig will gradually replace the regular smoking, not be in addition to it.