While none of the recomnedations in this thread worked exactly as described I was able to get the tavern cut scene to trigger by trying various combinations over and over and over again...
I believe the final combination ended up being; with dorian selected run over to a merchant, buy the cheapest item available, run back to the tavern, quicksave, quickload, enter the tavern.
I've no idea which part of that sequence actually tripped the necesary switch to make this work, but as I said, trying various combinations is recommended.
This game, in it's current rushed-out-the-door state, suffers from serious resource allocation issues which are generally responsible for **bleep** like this. Unfortunatly that means there is little you can do to fix things, aside from beating your head against the problem over and over again. Or wait for a few more "stability" patches.