I'm glad you asked. It seems that I was vaping at 3.5 v on a 2.2 oHm rebuilt coil (ProTank). I'm not sure why my ProVari was set so low.
No wonder the taste was lacking. I turned it up to 4.1v and now everything tastes fine.
1.8-2.5 oHm coils, 3.8-4.2 volts seems to be the sweet spot for me, with tobacco flavors.
edit: Now I remember why I had it set to 3.5v. I had a Aga-T with a 3.0 oHm coil on there earlier. I need to rebuild that one with lower oHms. 4.1v just gave me a burned taste.
I don't do the Watts conversion. I just vape to taste. I know if I make my coils within certain tolerances (1.8-2.5 oHms) I can get a good vape out of it. Certain dessert flavored juices require the voltage to be in the 3.5v range for me, but that is the exception, rather than the rule. I vape most everything at 4.2v when using silica. I'm finding that cotton is less forgiving, but easier to work with when rebuilding coils.