Going on a first cruise in late October

Your Euro city of destination to catch your cruise line is Rome so you would have to go through customs and immigration there. You are just having a layover in Amsterdam and not leaving the airport.

We went on our first river cruise last year, but it was through another company. We let them make our travel arrangements because it was less expensive.

Unless you plan to stay in Amsterdam for a couple of days, you might consider going straight to your destination.
I would highly recommend you arrive in Europe at least a couple of days early to adjust to the time change - you will have a 9 hour time difference. You will enjoy all of the cruise and not spend part of it adjusting to the jet lag.
Other posters will be able to address your customs and immigration questions if they cannot be answered by your travel agent.
Enjoy planning and have a great trip!

"Our travel agent says it should work."
Well, that doesn't sound very reassuring to me. What if it doesn't? Is there not a routing Portland to NYC to Rome? Or Portand Vancouver to Rome? I will echo what others have said and hope you plan to arrive in Rome at least one day ahead of the cruise departure. Your TA should suggest that, if he/she has not already done so.

Since Amsterdam is your first city in the Schengen zone you'll go thru Immigration (passport stamped with arrival into the Schengen zone) there. I would NOT go with a 90 minute transit time. In Amsterdam sometimes you land on what feels like a distant runway and taxi for 15 minutes or more. The airport is convenient in that it is all in one terminal but I'd want a later flight to Rome. There should be flights on whatever your major airline (or it's partner airlines) is every couple of hours.

You will go thru Customs when you leave the airport in Rome but that is just a door you walk thru that says nothing to declare.

If your Travel agent says it will work, ask them if they personally have done an international to domestic transit thru Schiphol in that amount of time.

There is a nice Delta flight from PDX to Amsterdam so you can avoid changing planes at any of the big cities on the US East Coast. Looking quickly at flights from Amsterdam to Rome on KLM, a Delta SkyTeam Partner, I see flights at 935, 225, 4:40 that are non-stop.

For myself, I generally want a 3 hour transit time when I am arriving on an international flight. I will go 2h30m at Amsterdam but I've been thru there before and can find my way. IF I were changing in Paris or London I'd want the full 3 hours.

If your flight from Portland is delayed at all, or you happen to get in to Amsterdam when loads of other flights do and lots of people are making their way to immigration, that could make things iffy. Having said that, Schiphol is a good airport for your situation - easy to move through, good signage, easy to make your way from your arrival gate through immigration and on to your next gate. So you won't be hanging out and relaxing there, but I'm inclined to think your 90mins is tight but easily doable. Indeed, I think Schiphol might even be the best airport for your situation!

Amsterdam is your point of entry in to the Schengen area/zone, so you'd be clearing passport control there. Keep an eye out for express immigration lines in Amsterdam - I do believe they have monitors/signage pointing to these lines for people who need to clear immigration quickly so they can make their connecting flight.

If you are flying on Delta through Amsterdam, you would appear to be arriving at Amsterdam at 8:15 in the morning. For a random day in October, I am seeing an 80 minute connection time at AMS. This is a legal connection. If you are delayed landing, there are many flights on KLM or Alitalia throughout the rest of the day from Amsterdam to Rome they can put you on. So be an optimist, you will get to Rome that day, and you might get there quickly.

Very much agree with others to arrive in Rome at least a day or more before your cruise departure. We spent three night in Rome prior to our cruise and loved it. Also hope your travel agent mentioned it's about an hour and a half from Rome to the cruise port so they should arrange the transfer from Rome to the departure port for you.

I was just searching on Kayak and it looks as if there are no nonstops between Portland and Rome, so since you have to do a one stop, having your connection in Europe is far preferable to having the connection in the United States. I agree with others that Amsterdam is one of the better and more efficient airports, but I do think I would like a little bit more of a buffer for the connection if at all possible.

I cannot emphasize enough what others have said about flying in at least one day before the cruise starts, preferably two or three days, especially if you have not visited Rome before. It is a magnificent city. On a similar note, consider staying in Barcelona two or three days after your cruise concludes. This may give you more flexibility with the flight as well, both pricewise and schedule wise.

Is this your first trip to Europe, or is it just your first cruise? Answering that question will help us help you better. If it is your first trip to Europe, then you will definitely want to add more time for navigation. Europe is wonderful, but there is definitely a learning curve for traveling there as compared to the US.

By the way, I did a similar cruise last summer and I really loved it.

Flying a day before the cruise is a different issue than transit time in the Amsterdam airport. There are so many collective unknowns that it is imprudent to fly and arrive the same day the cruise leaves your embarcation port. This would even be true if you were flying to a Mississippi River cruise in the USA. (At least it would cost less to catch up with the boat there!)

If your travel agent issued the ticket (note that I didn't write "ticketS") and it's one airline all the way, then your airline will have to get you to Rome. If they are two separate tickets on two different airlines, then you are taking a big chance. Do you have Travel Insurance? Does it include Trip Delay?

There are established minimum tranist times, set by the airline business. What does your agent say is the time in Amsterdam?

Just agreeing with everyone else. You DEFINITELY want to get in to Rome the day before your cruise departs, and this would be true even if you were on a nonstop flight from the US. Too many things can go wrong, and you don't want to miss your embarkation.

If you are flying in a day early, your 80 or 90 minute layover in Amsterdam is fine. Flying from Portland through Amsterdam to Rome all on one ticket, you will go through passport control in Amsterdam and customs in Rome. Customs is just a matter of walking through the "Green Channel Nothing To Declare" line. Unless you're "randomly selected for additional screening" (possible but rare), you're done.

It's passport control that can take time, and how much time can never be predicted. However, not only is AMS an efficient airport, but if you miss the connection, you will be put on the next available flight at no extra cost to you. Since KLM and Alitalia are in the same alliance (SkyTeam), there will be lots of options for Amsterdam to Rome later that day.

All of the above only applies if you are on one ticket from Portland to Rome. Don't let yourself be on separate tickets; if you do, then YOU are responsible for any missed connections, both logistically (no airline will help you) and financially.