I haven't been paying attention lately so I might be wrong, but CO and UA will be coming together in some fashion fairly soon (right?). Sign up for UA's mileage plus and you'll get 10k miles when you graduate, and their credit cards all have bonus miles as well, and there is no reason not to get both the personal and biz cards. Get a CO one as well. Put tuition on the UA card for double miles for the first $5k, then use a refund check to pay the card off.
Doesn't thank you network pretty much translate a point into $0.01 towards the cost of a ticket or something like that? If so, that is garbage. I have a citi card that earns thank you points and haven't touched it in years.
Southwest would be good if you never plan to use rewards for anything fun or expensive (premium cabin international travel). You would also have to fly Southwest, and it's up to you to decide if that is a pro or con. 5% cash back on restaurants probably wouldn't add up to that much, you'd probably save more just drinking water instead of a coke at dinner or having one less beer per week.
Considering there are only two other posters and I apparently disagree with both of them, I guess the best answer is decide what you want to do and then find the card(s)/bank(s) that best allow you to do it. It's going to be different for everyone.
If you are just after easy miles, sign up for all the FF programs (it's free, so why not), and go after some credit card and promo bonuses. You just missed the DL Bosley and rental car deals, but these things pop up here and there.