That's better than my way; so far I have been wholly unsuccessful in redeeming them for extra lives in Contra.

OP, welcome to FT. Now, to try and answer your questions:

- the best time to use e-Ups is whatever time works for you, as long as you remember that allll the other frequent flyers have them too, including a whole bunch of 50K, 75K and 100K. So, you might pick a flight that feels like a good fit, but then not get to use them because the last two open seats in J were given to higher-status fliers who wanted to use THEIR e-Ups on that flight.

- They expire February 29, which also means that in January-February, there are lots of 100Ks trying to burn through their leftover credits before they vanish.

- Until you hit 100K, using e-Ups for flights outside North America comes with a pretty steep fee, hilariously named an "Add-On". So, personally, I would say the best value for e-Ups for lower-status fliers is on the domestic long-haul routes like YVR-YYZ, when you can get them.

- Try to think ahead; for example, it would really suck to upgrade a YWG-YVR return trip on an E90, for 16 credits, and then realize you're 1 credit short to upgrade that YVR-YUL leg on a 333.

- As for "free" upgrades, if you're comparing Air Canada to Delta, United or American, the answer is "virtually never". Air Canada says they're trying to be like Cathay, in that they only upgrade people for free if the lesser cabins are oversold. That said, it happens occasionally and sometimes without rhyme or reason.

I'm not going to attempt to explain the priority for upgrades, there are several great threads on this board explaining it far better than I ever could.

Some people like Canadiancow and Mrs. YVRGary have great luck with their e-Ups, others refer to it as "Aerolotto" since your odds of success are not always high.

Your mileage may vary, as they say.

Good luck!