Hate to say it, but it really depends...I've sent pictures from the crater of Mt St Helens, but then not had service when down the side of the mountain...the same goes for everywhere you go...there can be signal is some places you'd never expect, but you could be SOL even in the middle of a city (there's a dead spot on a road near my house, perfect signal everywhere else).
Your best bet is to assume you won't have service 'in the woods' - then if you do, yay!
As for streaming, that's also highly variable. Tethering will really affect your laptop's bandwidth...if you can get a netbook or similar w/built-in antenna, you'll likely get much better speeds (in some cases 2x what you would get with tethering).
I can say with full signal, tethered via a tilt through ATT's network, I can stream youtoob without any major problems, but not HD. I've also successfully streamed the webcam via tethering (always fun if you've got friends back home that want a peak into where you are at).
One drawback of using an integrated 3G modem is that you have more flexibility on where your 3G antenna is if you are tethering a phone - you can move it a around and find the best spot for service...use Bluetooth or get an extended USB cable...this doesn't seem important in towns/cities, but out in BFE you might find your tent gets no service but 10' away you get 3 bars...huge difference when talking about data.
A couple other thoughts on a month+ trip (might be things you already know, I had to find out the hard way on a monthlong trip to Alaska).
- If you can, burn your pictures to disk regularly...every couple days...on a trip your laptop will get more abuse, last thing you want is to lose all those great pictures.
- Go on a couple trial runs beforehand...don't even have to be overnight (although that would be ideal)...make sure you know how to get everything tethered/hooked up right...nothing sux more than wanting to relax at the end of the day and watch a movie only to have to mess w/your settings for an hour trying to get things to work.
- Watch data plans/roaming in Canada...I got a nasty cell bill surprise when I got back from a visit to the in-laws in BC...and if you are near the border, check your provider...I've actually seen my phone switch over 1/2 mile from the border.
- Set up a website and keep us all informed...you can set up basic FTPs to sync your pics every time you stop or have service...press a button and walk away (make dinner on the fire or whatever).
...and maybe more important than anything...technology is supposed to make life easier, not supplant nature...don't spend so much time watching a movie you miss the moose or bear walking through your campsite...don't miss a sunset because you are watching a show you can DVR and catch up on when you get back...if you spend more time looking at your computer than out the window, close the lid and stream real-life instead
HTH
