Times have changed. You can't do a visa trip accross the boarder into Canada and back again. You need to be out of the USA for two weeks. You maybe OK if it's 10 days.
I flew out of New York last year to Australia for 10 or 11 days and was fine.
The chances of getting a full 6 months when you come back is not very great. When I came back in they gave me 6 months, but I had only used 3 months of my previous 6 month entry. So my total time in the USA was 9 months. The immigration guy said I would have great difficulty getting back into the USA in under two years. Subsequently I found out they have a guide line of 9 months in 20 months.. Yes, weird amounts!
Anyway, I wouldn't bank on getting 12 months. In fact, I wouldn't plan on it at all... Plan for two weeks in Canada, and then back for a total USA time of 9 months.