We have a trip upcoming on January 29, so it's certainly too late for us to make any decisions based on the current rate. Having said that, throughout the year I keep a running spreadsheet of our current trip budget, which includes the exchange rate. I watch it carefully and adjust savings as necessary. I was a little concerned just prior to Christmas and set myself a threshold for when I was just going to buy all of my US cash at that time and accept the rate. The rate stabilized and came down, so I held off and will use my credit card to gain the extra points.
Just to put it in perspective though, the current rate that I am using in my spreadsheet is the MasterCard rate of 1.3616220. Our total trip cost in Canadian dollars with that rate is $32,276.54 (A lot, I know, but it's 2 weeks, 7 people, 2-Bedroom Deluxe Resort, includes everything - flights, accommodation, meals, groceries, generous spending, hotels, a few evening magic events, 5 nights in St. Pete at a 2-Bedroom deluxe resort, etc). If I drop the rate down to say 1.20 (just to give a wide swing), the Canadian Total comes to $28,843.94. So the difference is $3,432.60. Granted that is a lot of money, but in the grand scheme of things, and in the context of the overall price, it's not that much. If we use last January's rate of around 1.266096, the difference is only $2,028.82 from last year, all else being equal. So really, our trip is only costing around $2,000 more than last year where the rate was lower - not enough to stop us.
Just for interest sake - if I put the exchange rate at 1.0, the total Canadian cost comes out at $24,596.26....now wouldn't that be nice for an all expenses paid trip for 2 weeks to Disney World/St. Pete