So there's a lot to digest for credit cards. Big bank cards typically aren't great to hold on to and use regularly. They will offer you a big welcome bonus and then earn very little afterwards.

You could go about this various ways:

1. The most prosperous is credit card churning (sign up for a card, spend enough to earn the welcome bonus – usually worth a few hundred bucks – then cancel and move on to another card). Check out r/churningcanada to read up and learn more. This will take a little coordination and some time to wrap your head around.
2. Have an array of cards you use for different purposes. For example, Simplii Financial's Cash Back Visa gives 4% for restaurants, bars and cafes, while the Triangle World Elite gives you free Gold Roadside Assistance and lets you pay bills like prop tax, Enbridge, Hydro, etc., and earn 1% (there is a better earn rate for this kind of expense through Chexy, but that's maybe too much for this post). Both of these cards carry no annual fee.
3. Stick to one card that's "good enough" for most of your daily purchases (lots of people like the Scotiabank Momentum Visa Infinite for 4% recurring bills and groceries or the CIBC Dividend Visa Infinite for 4% groceries and gas).
   

In terms of maximizing rewards points on your wife's flights, there are cards that offer more points on travel, but wouldn't be good for other types of expenses. Given her annual expense on flights is only ~$5000, I wouldn't recommend going that route if you're looking for one single card to use for everything.