This thread is helpful, especially with many people buying nic liquid for the first time right now. I guess all I can contribute is that the higher mg nic, 60 or 100, has to be handled much more carefully - gloves and plenty of ventilation, maybe eye protection too. Fumes from these higher levels are more toxic and if it gets on your skin, wash immediately.
I use 12mg and my wife's at 16, so I get 48mg liquid because it's a good deal, relatively safe and the math is easy.