I thought I had the whole thing figured out by knowing the loads before hand also, but then one flight canceled and the 200+ pax on board got rerouted on all the other carriers that had open seats. The one cancelled flight actually caused a domino effect for over 2 days. I spent $700 one way and that was the last seat 24 hours later. While there may appear to be a lot of open seats, it doesn't take much for them all to disappear. Figure out all the options for return before you go and leave yourself as many backups as possible. Also try to be as flexible with where you will go as possible since flight availability may change quite a bit shortly before you leave. I don't suggest booking any hotels that you can't cancel with little or no penalties. If you find some great hotel deals that you can easily cancel, you may want to book hotels in multiple destinations and then cancel the ones that you can't get to when you get your flight over. I've spent over $2000 buying tickets when I ran out of options. I hope you have better luck than I did. At least with the world economy in the tank there is a better chance this summer than any other summer in the last decade or so.