Had a look at MAN-SEA for an upcoming trip but decided against using TCX....US West Coast is too much journey in Economy after long days working. Not so bad if you've just been on holiday I suppose.
TCX really need to sort out the consistency of their long-haul product if they're looking for long term long-haul success. I was talking to one of their resident agents at JFK some weeks ago. She said even they aren't sure when Premium is available on the route and on which days....god help the rest of us. She also said that when it is available, it's 'totally sold-out'. I don't understand why TCX can't be more commercially astute. There appears to be a queue of people (with me in it) who are happy to give them more money for more comfort.
My own anecdotal view of both JFK and BOS both of which I've used on a number of occasions is that there are plenty of people using the services for non-vacation reasons, including one really senior exec I was sat next to in PE at the end of last year.
For MAN-SEA...all economy...can't 'SEA' that one lasting unfortunatley