You can start looking for airfares now—and definitely sign up for alerts with Farecompare, Bookingbuddy, et.al., because sales could pop up at anytime; however, it’s usually too early to get a Fall season sale fare at this point (currently late March). We’ve just seen some summer sales recently after a longer delay than usual. Be sure to check out the booking sites and tips in our new user thread, at the top of this forum.

750 isn’t bad for this airfare, but you might do maybe $100 better, and I doubt you’ll do worse unless fuel prices skyrocket. I’d want to book this at least 1 month in advance (for Sept. travel) but like I said, a good fare could pop up earlier. Time is on your side at this point.

For such a short trip, I recommend nonstop flights if the price is similar to other flight options. Be aware that most transatlantic flights depart in the evening, and arrive next morning. So if your flight leaves late enough, you might be able to work and fly on the same day outbound. Coming back, you generally depart Europe late a.m./early afternoon, and arrive back to northeast US by mid-afternoon (same day). So don’t plan to be the freshest at work on Mon. a.m. You’ll probably want to nap away the jetlag as much as possible on Sunday — I’m just guessing at your travel days.

A quick airfare check turned up USair with $630 in Sept. (mid-week travel days) to Brussels—which is right between Ams and Par on train line(s)—and returning from Madrid. That’s a really good fare for this trip; it does connect at PHL each way, however.

To connect MAD, PAR, and AMS …

Definitely train between Paris and Amsterdam. Check http://www.hispeed.n…
Between MAD and PAR or AMS … definitely fly. Good that you already found Easyjet. They fly from MAD to CDG (not to far-out Beauvais like Ryanair does) for only about $10 more than Ryanair on dates I see —well worth it, in my opinion. http://www.skyscanne… showing some Sept. MAD>PAR or AMS only $35 with Easyjet.

I recommend you shop airfares BOS>MAD (or Par, or Ams), and PAR (or AMS) > BOS with the multi-city flight search on Kayak and Cfares.

Thank you so much Don! I am working on it right now!

If you end up with 10 days in Europe add more time to Madrid and Paris. If you end up with less than that I’d really rethink your plan.