Vancouver is a much larger town but there is still a nice atmosphere and there is tons to do includi

We're heading over to the States and Canada for Dec/Jan this year, planning to cover the West Coast then fly across to the East. It's going to be a cool experience- we're from tropical Queensland where 10 degrees c is a cool day! Would love some helpful tips for the itinerary we've put together so far!
Unless you have something specific you want to see in Portland, you may want to pass on it. The train trip from the SF area to Portland is quite long - about a day if I recall. Flying from Portland to Seattle isn't cheap. Only Horizon/Alaska Airlines covers that route and they charge quite a bit. There is NO ferry from Seattle to Vancouver,BC. your options are rail, air or bus - all quite good and fair priced- except the air option. Boxing Day is an officially recognized holiday across Canada. Most places will be closed. Travel options on Boxing Day are functional - VIA Rail and airlines are open, but volumes are large as many people head home. Can't help you on the East Coast stuff.
Via Rail operates in Canada; Amtrak is the US train company. To travel the route you suggest by train, you would have to do Niagara to New York City, New York City to Lancaster, Lancaster to Philadelphia, Philadelphia to Washington.
Victoria and Vancouver are two very different cities. Victoria is a smaller town populated with older people and students and visited by many tourists. It's lovely in December with all the Christmas decorations. There is a very good museum and lots of lovely places to eat. Butchart cheap hotels in los angeles Gardens gets all decorated for the season with lights and is supposed to be beautiful.
Vancouver is a much larger town but there is still a nice atmosphere and there is tons to do including many inside things and because of the time of year and the almost likely possibility of rain (probably no snow) you many find more to do. There are ski hills close to town that have snow if that is what you are looking for. There are many indoor malls and many museums and a really great art gallery. If I knew more what you were interested in seeing it would help.
With this amount of time, and so much to cover, it would be wise to fly to Seattle , skip Portland, skip Victoria (you simply don't have enough time to allocate to getting to and from Victoria) , and give Vancouver as much time and attention as you can afford.
gotta agree with Northwest Male - i'm not even sure that ferry directly from Seattle cheap hotels in los angeles to Vic runs in December. even if it does, it's expensive. going to Vic for a day just to to rush back to the Van airport isn't worth it. although, once in a while there's cheaper air fares going east than from Vic- but it's rare. make sure you check on that Seattle to Vic ferry. here's a link to carless travel around NW Washington and Southern BC:
... the Buffalo drop of your canadian rental car is one of the few allowed by some of the car agencies but it does allow you to tour the Falls area with a car... there are several flights from Buffalo to NYC...
Regarding Boxing Day - one thing that hasn't been mentioned is that it is the BUSIEST shopping day in all of Canada. The majority of stores are open because of Boxing Day Sales. Personally, I avoid it like the plague because the malls/stores are just insane with crowds... but it's far from dead on December 26th.
Back to Boxing Day - Robyn is correct for Vancouver but Ontario is way more buttoned down so I'd check to see if stores there are as crazy as stores here. Although if you are in Niagara cheap hotels in los angeles Falls, it's such a small town I doubt much will be happening. You might try to see if theres a winery open that day though.
In Ontario, if a store is in a designated cheap hotels in los angeles "tourist area" then they are allowed to be open on Boxing day. Course that also includes most shopping malls. Most grocery stores are open as are Hotels/restaurants. Some independent stores/restaurants will be closed. Niagara cheap hotels in los angeles Falls will be open.
Niagara Falls is a city of 83,000 and, with 14 million visitors a year, the top tourist destination in Canada. Although summer is the main season, the week from Boxing Day to New Years Day is the busiest of the year, with almost all of the 15,000 hotel rooms full. People come for the Falls, Winter Festival of Lights, the indoor waterparks, the attractions, and the largest outdoor New Years Eve concert in the country.
You are really trying cheap hotels in los angeles to do too much in the time you have. I'd choose either West Coast or East Coast, and not try to do both in one trip. As you are traveling in early winter, the West Coast will be better.
I'd fly to LA, rent a car, then drive up the Pacific Coast Highway, detouring to Napa/Sonoma if you're into wine and perhaps to the Sequoia/Kings Canyon National Parks to see the big trees (you can also see them in Muir Woods just north of San Francisco). You could easily spend a week or more driving between LA and SF.
Although I'm not hot about visiting Portland either, there are several interesting things to do around there: drive up the Columbia River Gorge, then visit Mount St. Helens. The latter will take you inland on I 5 a bit, but it's worth it to see the power Nature can unleash.
Is flying to LA your only option? Flying to Hawaii and spending a day recovering cheap hotels in los angeles from the jet lag and then flying to San Francisco may make sense. The train from Emeryville (San Francisco (Coast Starlight) leaves in the evening and arrives in Portland 17.5 hours later (mid afternoon). I have slept many nights in coach on this train on my way back home to Oregon.
I think flying from Chicago to New York (or Philadelphia) would make sense. The Amtrak Pennsylvanian goes west out of Philadephia through Lancaster. I'm thinking the Amish will be celebrating Christmas and not much interested in entertaining cheap hotels in los angeles tourists.