I'm looking for something similar for my dad, my son, and me, so I'm getting lots of great information from you here. Some of you are truly informed and well traveled, and I'm in awe of your expertise--thank you for your insight (especially you, Heidi!).
I've found a really useful website that maps ships' positions and routes: cruisemapper dot com. It's a great resource for actual ship routes as well as port schedules (all the better for seeing if the Monstrosity of the Seas will be in port with her seven sister ships the day your modest tug arrives for a four-hour visit, lol!). Good to know which ports will be inundated with cruisers.