If you are not full timeing your best bet would probably be a wireless card. Just make sure that whichever one you get can work in the areas you are normally in. Since I am full-time I have a MotoSat mounted on the roof and all I do is push a button and it goes up and find the satellite and locks in. When we are ready to leave I press the Stow button and it goes back down. We always need a clear view of the southern sky, so that means a heavily wooded RV park is out of the question for us. The service is through Hughes Net (Formerly DirecWay). It is kind of pricey but like I said we are full timers and it was worth it. Do not believe something like that would be worth it for weekends for a few long holidays during the year. There are some in which you can buy a stand and set it up outside yourself and could use it at home. We were able to use ours from PEI all the way over to Hamiton, Ontario. Never a problem getting Internet. I am looking forward to trying it in BC. I have not been there in about 6 or 7 years.
We are fulltimers and use Verizon wireless card and most of the time it works as long as there is a tower in the area. We have found some places that do not work but we just grab the laptop and go down the road a few miles and we have internet. Unlike Joseph's Motostat which is permanently mounted and needs the southern sky we just need a tower and trees do not matter. I would like Motostat just cannot afford it.
We use a Sprint Aircard for internet and AT&T for Cell Phone. We have been places where we did not get cell phone service but our Sprint Card worked.
One thing about an air card. If you are in a good area you will most likely receive EVDO Service. If you are in a remoter area you will most likely receive 1x service.
The EVDO is like DSL at the sticks & bricks, only my EVDO was faster. 1x is like Modem service, slow but you can get email and some services that don't require a lot of load time. If you stay in remote areas like National Forests and some State Parks you may not get a good Air card service. Many cases if you have a tripod Sat Service you might find an open area to the south. Both have their advantages and disadvantages.
Call the 3gstore.com if you want to use an Air card. They can help you with a lot of options if your not highly computer knowledgeable. Do a lot of research before you make a choice.
I use a Verizon air card on the road and am pleased with it, I deliver mostly in Alberta, Saskatchewan and British Columbia. Phone is ATT blackberry curve with blackberry global internet service.
Up in BC, AB, SK I am always roaming on Rogers. Verizon gets really pricy up there, don't hardly use it in Canada anymore after my $300 bill for internet service a few months ago and unfortunatly I can't tether with the Blackberry global service which doesn't cost me extra to use north of the border.
I also use a Verizon Wireless card, it is far from free but a lot more secure. I also have an external antenna and an amplifier both Wilson. We have been satisfied with its coverage, I am also on the internet daily.
We use a Telus Air Card. It works very well for us. We have the plan that gives us coverage throughout Canada and the US. We summer in a fringe cel reception area and so I purchased a signal booster for our card and cel phne. To date, we have not had any problems.