Capstan Blue and Samuel Gawith Full Virginia Flake are pretty light as far as Vitamin N goes, though I'd avoid C&D's red Virginia offerings like Yorktown and Opening Night since they tend to pack a pretty good wallop for Virginias.
The good news though is that all you really have to do is keep smoking what you're smoking right now and your body will adjust to it fairly quickly. I remember when I first started smoking Gawith's dark fired blends like Kendal Dark, Dark Flake, Dark Plug, and 1792 Flake I'd be running to the bathroom to park it on the toilet after 20 minutes or so of smoking every time.
After about 2 weeks of smoking them every couple days though my insides got used to the higher nicotine content, and now they don't cause any intestinal distress at all for me. It just takes a little time for your body to become accustomed to the nicotine.
