WARNING!
If you are just planning on "roaming" while you are up in Canada, you had better check with Verizon before you go.
Wireless companies are making a
ton of money from US citizens who go to Canada for a week or two, and use data up there. My nephew got stuck with a $2400 bill, which his (ex)cellphone company refused to budge on. I tried to help, but they will not take a penny off of his bill. And, they are currently going after his credit rating as well.
You need to realize that with the advanced operating systems in these phones, they are constantly communicating over the data network. It will be hard to keep your phone from doing so, unless you keep it in "Airplane Mode" except when you have to make a call.
Text Messaging may also be charged on each message sent/received, even if you have an "unlimited" plan in the US.
Regarding the data rates: I just checked on Verizon's website, and they will charge $0.002/KB of data, or approx. $2/MB. That can add up quickly.
When my wife and I traveled internationally, we followed the customer support person's advice:
Keep your phone turned off unless you absolutely need it.
Unfortunately, this won't work with an Android phone, since it is never truly "off" unless the battery is pulled. So, keep it in "Airplane Mode" instead.
Hopefully, my 2 ¢ will save you thousands.