I've been reading up on the complications of Border Control when flying from the US to Canada to take advantage of the great J fares to Europe.

Is there an easy, if time consuming, way to go SFO-YVR then board a UA flight Yvr to ORD to LHR? All in one connection? We have Global Entry and Nexxus.

Should I be conservative and just fly up to Vancouver the previous day and stay in a hotel the night before?

Thanx and a tip of the hat to those who know the score!