The first playthrough is going to be 100% single-player. I cannot really fully experience the game with other people. I have some friends who love BG and D&D in general but who skip the voiceover as soon as they finish reading the subtitles, for example.
I think that a story-driven game should always be experienced as a SP. You will never allow yourself to experience all the emotions a game wants to transmit if someone is watching/chatting in the background.
After the first run, I'm totally going for a multiplayer one though
