I like the font treatment on #151 but not on #190, where it's too big and all the same color. Also, what would it look like to add some color (orange perhaps) to one or two of the bubbles?
#173 had a very interesting treatment of the little box which gave the indication of a conversation going on. Since our business includes social media marketing, I like the tie-in of that. Perhaps the top bubble could have a tiny little bit of stretch to one of the corners (similar to #173, but not as obvious) to indicate the conversation. The bubbles already do this, in my opinion, but it would add something extra to it, don't you think? Maybe that one could be the orange one.
I like it #197. Might need to tweek the position of the bubbles but it's the idea I'm after. Could you also do it with the text below the mark like in #151?