I've had extremely large duffel bags (with wheels) on Acela, NE Regionals, SWC, EB, CL, Surfliners, The Card (before checked baggage was reinstated), and the CS. When I travel to RTE from PHL I always step off at NYP and take pictures of the Toaster or Banana, or in Acela's case power cars. My carry on's consist of: A laptop (which doesn't count towards the limit), a backpack, and a camera bag. Sometimes I need to carry two suitcases. IF checked baggage is available I will check the bags I DON'T need. I will have a set of sleepwear in my backpack if in a Roomette or Bedroom. When I took the SS from PHL to ORL and visa versa I had two suitcases. Both went through checked. I had a medium bag and a small bag. Sadly the small bag is so small that I have to bend over to roll it. I bend down about 2 feet and I'm 6 even. The only problem I had with checking the two bags was on the way down one of the legs broke. Amtrak had no part in that. It was broken before so I couldn't call Amtrak and say hey you broke my bag! When I returned and picked up my bags at PHL there was a odd green dust on the bags. Has no clue what from but that was my only complaint. The bottom line is, if you can check bags do it! You get 3 bags checked for free per person. After that they charge you, I forget how much but they do. I love checked baggage on Amtrak! Because it's FREE!
Steve