3 Cities in 9 Days (Amst, Paris, Zrch)

I personally would do just Amsterdam and Paris with your time frame. You have to consider you are going to lose one or two days to travel, etc. so you really only have about 7 days there. 4 days in Paris and 3 in Amsterdam are just about enough to really enjoy the cities.

You basically have a big triangle, so order from a logistical point of view may not be so important. First, definitely consider flying open jaw, into one of those cities out of another, avoiding a return trip to the first city. So play around with the options (Paris/Zurich; Amsterdam/Paris, etc) maybe one of those tickets will be hundreds less and make the order apprarent. I would also look at the transport between cities, Amsterdam/Paris is easy, direct and fast, Amsterdam/Zurich is longer, basically, if you could cut out a long travel leg, you are better off, or if you could avoid cost, also good

Ya I am thinking the same thing only do Amsterdam and Paris or add an overnight in Brussels in between assuming yu are takign the train between.
so I would either do paris 5, amerstdam 4
or paris 5, Brussels 1, Amsterdam 3

Many like www.kayak.com or www.skyscanner.com for comparing airfare. When you find an option that meets all of your needs, check with the airline’s website directly. I was recently able to secure a better fare directly from the airline.