Silmarillion: What would you add/expand?

I certainly agree that the story of the Fall of Gondolin in the Lost Tales is wonderfully heroic, almost along the lines of David Gemmell. One can only speculate what a proper rewrite would have given us - I'm sure it would have been much longer than Turin's story, with better characters, less predictable doom, etc. However, the only version we have should stay where it is, since it belongs to an entirely different era to the more up-to-date Silmarillion.