We have the Sapphire Preferred card and Freedom card from Chase, along with a Southwest card. Love all those free flights!
My father-in-law is a "travel hacker" - he and my MIL travel quite a bit and almost never pay for airfare or hotels. I'm talking at least twice per year, and they go to Europe. It's really amazing. He taught us a little about it but mostly said it's so time consuming that he almost doesn't recommend fully diving into it just yet like he does (he's retired).
I don't understand DL hotel pricing either. I mean, I do - they price them that way because they CAN. I need to better research of-site options...