This will be a little long but: The train is the best!!! And this may help more than you!! This is based on my own experience and info from some very kind Seattle ladies
Amtrak business class car has less seats than the coaches. It is 2 and 1 seating vs 2 and 2. So it is more controlled in terms of seating when you get on the train, although you still don't get assigned a specific seat the last I knew. You may be offered pre-boarding but since there are fewer seats, the mad rush to get a seat should be less of an issue. You do get a free newspaper and unlimited juice and soft drinks. Tip: sit towards the middle of the car to have a smoother ride (wheels are at the ends). The other thing is to look for a wide window on the left side if you want to see the Puguet Soumd - great view!!!
I took the train at 7:40 am (4 hour ride) to Vancouver when I took the Alaska trip in 2009 and the coach seat was fine. I actually ended up in the cafe car for most of the trip talking to someone who had graduated from my school (Central Michigan University) although she was a lot younger, and straight, the time flew by!!!!!
Re airfare. What I did was fly to Seattle on Saturday and take the train to Vancouver (Jet Blue had a great flight sale.) on Sunday. Then Sunday after the cruise, I was booked on a Delta flight from Vancouver in the early afternoon to get back East. Since you are in Florida, you may want to wait a few month to book the air. After the cruise if you take train from Seattle and so want to fly back from Seattle to Florida, you will need to stay in Seattle overnite since the train does not leave Vancouver until 5:45 pm. or you could take the bus.
Re hotels and getting to downtown from airport.
Days Inn, Best Western, Sixth Ave Inn, 8th Ave Inn, are all decent, safe, and less expensive. Your cab should be cheap to Train station they are about 12 block away. Anything in zip codes 98121 or 98101 are very close to the King Street Station where the Amtrak train to Vancouver leaves from.
I flew into Seattle the night before the Cruise and stayed at 8th Ave Inn. It's just across the street from the Westin, so you'll have a short half-block walk if you take the Airporter bus from airport to downtown
Depending on how much luggage you bring, there's a bus-to-light rail connection from the airport to downtown which runs about $2.50, by the way. If you've got one roller bag and a backpack, I hear that the bus drivers will be nice and give you time to get yourself and your stuff on board, and the light rail goes to within not many blocks walk of several of these cheaper downtown hotels.
There's a nice food court at Westlake Center, which is just a block away from the 8th Ave Inn ,so you can get something decent and not expensive to eat for dinner. Or if you want to splurge, I ate at the Dahlia Lounge on 4th Ave, which is only a few blocks away from 8th Ave Inn (trendy but wonderful!!!) Or to really splurge, Flying Fish on First Ave, lesbian-owned, very fancy and was recommended to be very tasty.