When US CBP asked if I was "presenting, or attending", I did NOT take the opportunity to explain that everyone was expected to participate and present :)

I know that b/c my lifestyle is sometimes "unusual" while at the same time I have a strong inherent tendency to be very correct and "overly" honest. :D

"Why are you visiting Canada?"

"I"m here for a conference"

"What's the conference about?"

"Computer vision, you know, programming research"

"How long are you staying?"

"A week"

Stamp

There was a point on the outbound journey where they were checking everyone's passports by the scanner (i.e. you'd go through and everyone would set the alarm off, but it seemed to be a passport check rather than anything else), as soon as they saw it was British they lost interest.

It does, the lineups at Toronto's Pearson Int'l airport are longer for Canadians in my experience.

This is very good advice, anyone prepping for depositions would have heard it already but it works very well for border personnel too.

"On vacation."

Done.

On the other hand, I've gotten across with no delay at all by saying "I'm picking up a friend at the Vancouver airport" and "I'm going to go buy this drill press off of Craigslist -- see this printout?" Neither of those is illegal, and in neither case can they expect you to have hotel reservations or know any Canadians, etc.

One of my favourite parts about driving to the border is going through scenarios with my passengers, and how to answer each question.

Honesty might get you in trouble, but thats still probably a better place to be than trying to lie your way out

So, sort of the same strategy used for patent claims?