Hey there,
That is great you figured out you can purchase through USAA since you have log-in access, even though you don't use any of their services.
For us, we of course include the full prices of the cruise, plus plane ticket fees (even if you use miles, there are still taxes you have to pay for your tickets, so we use airline miles to fly to Europe, but I include the taxes I've paid in the total cost I use for the insurance quote). But, if you pay full fare for tickets, then I add in the total airline cost.
I also add in all my private excursion costs I have booked just in case the day we arrive to the port we are sick or who knows what, and we last minute can't do the excursion and also can't get a refund from the private company.
Also, if you are doing any Disney excursions, I'd add the total cost of those, too, because Disney won't refund you if you are sick and can't go on the excursion (unless you get a note from the ship doctor and the ship doctor agrees you are unable to do the excursion... but you have to be in pretty bad shape for this to happen. I know, because this happened to me when I very badly sprained my ankle (grade 3 sprain) on the Disney Magic a few years ago and ended up in the ship ER ... yah, no fun at all!! But, the doctor had Disney refund my excursion because he agreed there was no way I could walk to go on the excursion we had planned. But, on the other hand, my father-in-law once developed a bad sinus infection and he had a snorkeling Disney excursion planned, and he saw the ship doctor the morning he was to go on the excision, and the shop doctor agreed he had a bad sinus infection, but would not write a note to refund him for that excursion because the doctor claimed he could just stay out of the water, but still go on the boat for the excursion). So, that is a LONG way of saying, it's very rare Disney will refund your excursion of you are not well enough to go on the excursion, so that is why I add the Disney excursion cost to my trip insurance quote.
As for hotels, I add in just the first night's cost of all of our hotels, because MOST hotels will charge just one night's fee if you cancel past their cancellation deadline period. Also, I figure if our trip was delayed due to circumstances out of our control (weather, etc), and we are a day late getting to our destination, I will know we will be late, so that will give me time to call the hotel and adjust our dates we are staying without getting charged, but I just assume the hotel will still charge us one-night's fee if we cancel or change last minute. So, that is why I just add only 1-night's hotel cost into our total cost of insurance quote.
Also, any other things you have pre-paid (car rental, train tickets, pre-arranged private taxi's, etc), I add in all of those costs because it's likely they are non-refundable.
So, to sum it up, I would add to your quote any money you potentially could lose if you had to cancel very last minute or your flights were delayed and you made it to your destination a day late. Just read up on all the cancellation rules for your hotels and private excursions (if you have any booked) and that will help you know if you should include those in the quote price.
And, yes, for the medical part, if your medical insurance won't cover you out of the USA (or in Europe), then you would want to get a good medical plan with your trip insurance, including medivac, or medical transport.
Good luck!