Earlier quoted context omitted.
Ugghh... this exactly. I recently turned down a "we will fly you to the west coast" interview with one of the big five because I couldn't be bear the idea of spending weeks preparing for the 4-8 hour day of whiteboard coding (only to not get selected anyways). Spent the time hanging out with my girlfriend instead. Worth every minute.
I think you almost played this right, with one caveat. You should have taken the flight to the west coast and done the interview, with minimal (hour or two) to no prep at all. Why? First, you never know. Maybe they legitimately want your skillset - why fake up some crap you hate for a job you don't need? Second, you'll get practice taking interviews in a very low pressure situation. Worst-case they laugh at you and y…
Having done this when I was younger and more foolish, I would not recommend it at all. I felt like I did pretty well overall, but ultimately flubbed a couple of [simple] questions that torpedoed my chances. While things worked out for the best (that company's future looks grim and I'm very happy where I am now), it was a blow to my confidence at the time.
I probably wouldn't have had to have prepared for a month or two to get that offer. A week of glancing at my notes for 30 minutes to an hour a day to refresh would have been sufficient. I think you owe it to yourself and the company who is paying to fly you out to at least brush up a _little_ bit (within reason) beforehand. It's almost like basic hygiene.