Hi there Cathal:
First off, when the NASL was the top league on this continent, the Whitecaps were a perennial power and won a title in 1979.  So, good luck to TFC, but they would not be the first.  Fond memories come back, watching Bruce Grobbelar, Alan Ball, Carl Valentine, Roger the killer Kenyon, and even Bobby Lenarduzzi, who I used to yell at "Kick it to a white jersey next time, Bobby!!!"  Others might recall Gerry Gray trying to score from midfield, and always blasting the ball 25 feet over the net. We saw the greatest, Pele, at Empire Stadium.   Final note - don't assume Seattle can't handle cold and rain, for heaven's sake - there is a reason Vancouver and Seattle both sell t-shirts saying "Seattle Rain Festival: Jan 1 - Dec 31."