It sounds like you are flying Northwest Airlines or one of it's partner airlines. We used NWA on our Italy trip this year. Our inbound flight was slightly different since we had a weekend stopover in London before we went to Rome. But we did fly from Detroit to Amsterdam and connected to London.
You should receive all of your tickets in Baltimore for all connections. Your baggage will be automatically checked through to your final destination. You will not see your luggage again (hopefully
until Rome.
Not to make things complex, but there are different procedures at AMS for Departures depending upon which Hall you are in (i.e. based upon your destination). My memory is that in AMS after arrival, you will pass through Immigration and show your passport. No declaration for customs is necessary and you will NOT collect your baggage. You will walk up to a central area that has many large shops, restaurants, and even a casino. Departure gates can be accessed directly by walking.
Our Departure gate had it's own X-ray machine and a holding area. People queue up outside the gate holding area single-file. I did not see any preference given to folks with Business Class tickets for boarding. Your carry-on luggage will be screened through the X-ray machine at the gate.
Arriving in Roma, you will go through Immigration Control and then wait for 40 to 60 minutes for your luggage at baggage claim. Things move very slowly in Italy. I was surprised that the
ABD representative was allowed into the baggage claim area and hence I wasn't looking for her while we patiently waited for the luggage. We did have a nice conversation with a British Airways flight attendant who lives in Rome.
-- Return trip home:
KLM/NWA basically has two flights from Venice to Amsterdam (6:20 am or 12:00 noon). We flew the early morning flight.
The Venice Marco Polo airport operates a little different than many other airports. The ticket counter where you must first check-in will not open for your specific flight
until 2 hours before your flight time. You can arrive 4 hours early, but you will not be able to go to the ticket counter until 2 hours before your flight. There are electronic sign boards that indicate when your flight is ready for check-in. I would try to be there at least 2 hours before departure.
We left the Hotel Dei Dogi at 3:55 am by private water taxi and arrived at the airport dock at 4:10 am. We were the only boat on the water (read: zoooom!). There was a driver and a van waiting for us at the airport boat dock who drove us for 90 seconds (yes, 90 seconds) to the front of the airport. There is a walkway from the boat dock to the airport, but apparently ABD feels it is too far for Americans to walk (puzzling, after having walked all over Rome, Florence, and Venice).
The Venice Marco Polo Airport does not really open until 4:30 am. The doors are open for entry, but there aren't any ticket counters, etc. open before 4:30. There is a large electronic board in front of you as you enter the airport. The board will tell you which ticket counter to go to for your flight number (KLM/NWA is on the left). Expect the gate number to appear at about 2 hours before departure.
After checking in at the ticket counter and giving them your luggage, you will then pass through security. Security moves very very slow. The good news is that if your luggage makes it on the plane they will hold the plane's departure until you board. International planes won't depart with extra luggage. They have to unload the extra luggage (or wait for the passengers, which is what they do).
When you arrive in Amsterdam, you will pass through Immigration Control again where they will check your passport. You can then walk to the central shopping area.
Now here's where things change. For the departure flight from AMS to DTW you will go through a personal interview at the departure gate. You will queue up outside the gate area and then family-by-family you will be interviewed by a security agent. They may ask very detailed questions about your vacation, how your luggage was handled, etc. Has your luggage always been in your possession? Did a Bellman assist you? (Hint: Then it hasn't always been in your control.)
After the interview, your carry-on luggage will pass through an X-ray machine and you will be herded into a small holding area.
If you need help, just ask one of the friendly people in the Sky Blue KLM uniforms in AMS. It is highly likely they will speak excellent English.
Arriving in Detroit, you will collect your luggage and go through customs. You will present your passport and declaration form listing all of the things that you purchased.
It sounds daunting, but as someone previously stated: Just follow the herd. Look for people with dark blue passports and do what they do. If everybody around you has a maroon passport, you are likely in the wrong line.