Although I am a committed dark chocolate fan, my taste tends to stop at around 80%, where it can start to get rather bitter (I still have a bit of a Tcho 100%, which is essentially inedible). To my surprise I have tried and really liked this Lindt 85%; it's pretty smooth and still just sweet enough. The dark flavor is very substantial, and discourages eating too many squares at a sitting (2 to 4 are quite sufficient).
I have just spent a few days in NYC, and tried to find some legit dark drinking chocolates, which are surprisingly easy to find throughout the city, albiet at a high price. The first one tried, also coming up #1 on Yelp and a couple other websites, was at Mariebelle Fine Chocolates on Broom St. They had a 65% and a 70%; I tried them both and opted for the 70% because it did not contain extra milk, although the ingredients lifted milk in the mix. It was pretty bitter and strong, and I had to add a packet of sugar to help get it down. The buzz did remained for a couple of hours, and I'll have multiple opportunities to adjust the mixture at home with the bag of mix I purchased ($7 for the large hot chocolate, $21 for the mix).
Both NYC drinking chocolates were very serious, adult drinks, but I admit I find West Coast chocolate and chocolate drinks to be not necessarily sweeter, but smoother and a bit more palatable.