Nice job!!  here are a few suggestions:

Writing Practice

A: Have you changed your mind about the destination for your next vacation?
B: Why should have I changed change my mind? I think Australia is a quite interesting place to visit. Don't you think so?
A: Sure it is, that's not my point. It's just that Australia is very far from here. I believe it's kind of 20 hours or something like that. You told me that you planned one-week holiday and I suppose the flight isn't cheap. That's why I was wondering thinking that you might have been having second thoughts.
B: It's not as crazy as it seems and, as matter of fact, the airfare wasn't that expensive. I got a pretty good deal on a new booking website that is trying to carve a niche in the market.
A: I can understand that but to me the time you'll be able to enjoy your vacation doesn't pay for the trip. Not to mention that you'll be right back at work when you'll be returning you return.
B: You're probably right, but it's too late now. Everything has been set. I'll be keeping a positive thinking. positive thoughts.
A: I wish that'd be enough. I hope that's enough.  Good luck!

Thanks in advance for you feedback.