I think that I am easy to satisfy when it comes to good hotpot. But unfortunately, it is not always to either find a good hotpot restaurant, or else find enough friends who also want to have hotpot together.
Fortunately, most people like to have hotpot during autumn or winter in Beijing.
One of my favourite hotpot places in Beijing is this restaurant called 海底捞, or Haidilao in Hanyu Pingyin.
(I find the name of this restaurant rather special, actually. I always get the impression that it comes from the Chinese phrase 海底捞月, which translates literally to "fishing for the moon at the bottom of the sea". It actually means "striving for the impossible", since you can never fish the moon out of the sea, the only thing you end up doing is disturbing the reflection of the moon. I don't think the restaurant name means that though. It is probably called that because having hotpot is kind of like "fishing" food out of a pot of soup...)
To me, there are 3 things neccessary in every good hotpot.