change planes in Munich or Frankfurt?

I'd use Munich. In May I arrived via Munich and processing getting my fingerprints and photo was fast and the transfer was easy. Leaving via Frankfurt however was very slow. I was in a line for over an hour. Once there the checking that my fingerprints and photo were on file was quick. It was good that I had more than an hour between flights.

Have not been through Munich for many years but would do anything to avoid Frankfurt as the two more recent times I have changed there were nightmares.

Munich Airport is more organized IMO, Frankfurt has just opened a new terminal though,
which may have improved things.

United is the Star Alliance partner that flies nonstop Amsterdam to Dulles, it seems like
Swiss or Lufthansa should be able to offer you that.

Look at flights out of Brussels in stead. United has a flight Brussels - Washington that they code share with LH.

Getting from Amsterdam to Brussels for a flight is easy. There is a even a direct train from Rotterdam to Brussels Airport.

Thanks for all the input!

I looked at United, and I see that while Swiss and Lufthansa have opened dates into June 2027, United only goes through mid-May, which is before our return. So that's why Swiss wasn't offering any United flights from Amsterdam. But checking fares using dates that are available, United is roughly DOUBLE the price, so...that's a nope. Hard to grasp why there is such a discrepancy.

I just flew through both last month and EES was mere minutes. I had about three hours for the layovers, and if you have that, either is fine.

Funny how we all have different experiences. I have been through both Frankfurt and Munich more than once, and Munich is the only place I almost missed a connecting flight due to the unorganized mess at security. It was a few years ago, though, so hopefully it isn’t like that any more. I have no complaints about Frankfurt. Two years ago, on my way to Istanbul, I had a couple hours in Frankfurt, and when checking the information board to find the gate for my flight I was approached by a helpful airport employee with an iPad who quickly found the information for me. I haven’t seen that anywhere else.

But checking fares using dates that are available, United is roughly DOUBLE the price, so...that's a nope.

That seems odd. Are you checking multi-city flights? Are you looking for business or economy?

I just plugged in IAD to ZRH / AMS to IAD on googleflights using random dates in April and the nonstop flights on United were about the same price as the Swiss or Lufthansa connecting flights.

Both United and Swiss have non-stops to Zurich. United has a non-stop from AMS.

Laura, apparently different airlines differ in how they display prices and that confused me. Swiss and Lufthansa show the prices ("From $$$") for each part of the itinerary (e.g. Washington to Zurich; Amsterdam to Washington) and add it up after you select flights. United shows the "from" prices for the whole itinerary before you select the first flight. At least I think that's what happened; makes sense.

At any rate, I've pulled the trigger and decided to use Swiss & Lufthansa and go through Frankfurt, for various reasons. I've learned from these boards that due to EU laws, it's easier to get compensation if a European airline strands you, and I don't like United anyway. Frankfurt has more flight options than Munich if things go sideways, and the layover time for that itinerary was more reasonable. I know they've just opened a new terminal and closed one of the old ones for a long renovation, so a year from now they should be adjusted to that change as well as EES.

Thanks to all who offered suggestions, lots of good options!

OP, I certainly understand your choice in airline. But, Lufthansa, Swiss, and United
all are part of the same alliance. This means that the itineraries they show may have
different airline flight #'s than the carrier you will actually be on. For instance, there
will be an LH flight number attached to a UA flight from Frankfurt to Dulles.

So, if you want to avoid United, check the itinerary you booked to make sure there
isn't a flight # something like LH 8847. This is a clue that you are actually on a United
(or other Star Alliance) airplane.

Airlines only load their schedules into the central database 330 days ahead of time.
Yes, some airlines load them sooner, but you can't always see them on other booking
sites other than the airline's own site. This is probably why you could see Swiss and
LH but not UA. Lufthansa actually owns Swiss now.

The EU compensation laws are in effect for European airlines for flights leaving the
US as well as Europe. They only apply to US airlines for flights departing Europe.

Finally, booking this far ahead of time, you should periodically recheck your flights to
make sure nothing has changed (you can't always count on the airline to alert you in
a timely manner). When a schedule changes, which 100% it will before your date of
travel, you have the option to rebook and perhaps take advantage of a lower fare.

Thanks shoeflyer. I'm aware of code-sharing and the Swiss site makes it clear who's actually operating the flight. I wasn't aware that Lufthansa had bought Swiss, though I noticed their websites were virtually identical. That makes me feel better, because I hate mixing airlines on a ticket. Too much potential for blame-shifting if things go sideways. Hopefully that's minimized since they're part of the same company (I can hope, anyway).

I am a little confused by your comment "So, if you want to avoid United, check the itinerary you booked to make sure there isn't a flight # something like LH 8847. This is a clue that you are actually on a United (or other Star Alliance) airplane." What exactly is the clue? The fact that it's a high number? I know it's not just that it's a 4-digit number because I've been on plenty of flights with 4 digits that weren't code shared.

I also know there's risk / likelihood that the schedule may change AND that they might not give prompt notice about it. Air France changed a connecting flight giving me 65 minutes to made a connection at Charles de Gaulle. I noticed it and wanted to change to an earlier flight from Nice, but they wouldn't do it without canceling and reissuing the whole ticket for $1000 more! I chanced it (it was the end of a trip so the schedule was flexible) and we made it, although our luggage took an extra day. (That was before EES).

OP, yes, it's the 4 digit high number that is the thing to look for.

For instance, on August 7th, Amsterdam to Dulles is United 947. That same flight is
code-shared as Lufthansa 7619 (operated by United).

thanks, good to know

United is roughly DOUBLE the price, so...that's a nope. Hard to grasp why there is such a discrepancy.

When United first publishes their fares for a distant date, I've often (always?) seen outrageous fares. When I check a few days later, the fares for those same faraway dates settle into a more normal price range.

My theory is that eager travelers might just pay the crazy first-published prices. Only a theory.

regarding the experience of navigating the airports, to me MUC has always been a clear winner over FRA, but last week in connecting through MUC the experience was much closer to the same level of unpleasantness as in FRA. This was Helvetica, also now part of Lufthansa, to a MUC-SFO flight that is operated by Lufthansa with many many codeshare flight numbers. The L gates at MUC have very few services or amenities if you are in the hoi polloi economy class.