I only book when I'm happy with the current price and schedule. For me time is also worth money. I'll pay $50-$100 more to get better timings. For instance I booked flights from San Francisco-Athens and Rome-San Francisco as part of a cruise.

For $75 more I can fly on Lufthansa, get United miles and arrive in Athens at 5:05 PM vs 12:00 Midnight or even 10 PM. On the return I can leave Rome at 12:05 PM arriving at 7:00 PM. These flights go via Frankfurt to Athens and Munich from Rome-SFO and are flown on Lufthansa which is my airline of choice for international trips.

What I figured out is by flying via JFK would add more time. I've flown during the winter where it took me 6 hours and 40 minutes to fly from JFK-SJC. I would much rather clear customs at SFO and even if my flight were to be delayed at least I'm 45 minutes from home vs 5 hours across country.

Customs at SFO takes about 45 minutes during the off season.

So paying the extra $75 is worth it.