Congrats!
I wouldn't bring up the tuition assistance pay back, maybe they won't ask for it?! My old company had a written policy like that. But they never asked for it back. (we work in accounting, so we knew that it wasn't enforced...) Then one time they did. My coworker that was quitting and 1/2 way through her two weeks notice. And she was like "hell no, we don't enforce that on anyone, we aren't starting with me." And our asshole boss said, "sorry lady, yes we are, it will be withheld from your last paycheck " We were paid currently, not in arrears, which is unusual, but she was like "I'm not working for free." And she left and never came back. Which I thought was awesome. (IDK, maybe some will disagree with me since that was the written policy. Maybe you had to know first hand what an ass our boss was to appreciate this.) When I left I only gave a week notice to ensure my annual bonus payout. I don't regret it at all.
Anyway, my point is that companies have little in the way of loyalty to their employees, or courtesy when it comes to laying people off. So I don't think employees need to have it, either. Give whatever notice is best for you, I don't think you need to be courteous to them. Good luck!