I'm an outsider on the TWA/AA merger, but I went through the Northwest/Delta merger.
I always thought TWA pilots were hard done by the integration. TWA was a proud carrier not long removed from the top of the heap. The reception they got from American's union and pilot group was hostile and arrogant.
We Northwest pilots took a bit of a seniority hit when the agreement was reached, but I have to say, a few years after the merger, that the handshake was always out there between us and the Delta pilots, the merger was done as well as I've ever seen one done, and today, the airline is seamless.
I thought from the beginning, and still do, that Northwest had a better flying operation, but Delta is a much better company to work for.