As far as drinking and canoe trips goes I think it depends on how it is used.  Obviously, it is a bad decision to drink and then paddle or portage.  If any drinking is done on my trips I make sure that all the work is done and that no paddling, swimming, or other potentially hazardous actions are taken.

I did a number of long northern trips in the 80's and paddled one one with a semi-famous fellow (not who you might think, I can't stand THAT guy) and we followed his tradition of a pre-dinner cocktail.  As the days were long and difficult, we had a system where once the tents were up, gear put away, and a designated person was cooking dinner on the stove we would have a small shot of rum and some salty snacks while we waited for dinner.  This was a nice way for everyone to relax and get together in cameraderie.  I thought that was a good idea.