You can also decide what data activity you want when travelling. Check Settings > Network > and select your options. You can restrict 3G, Cellular data, and roaming data. By choosing wisely, you will find all activity but calls & SMS can be defaulted to WiFi. Keeps the costs reasonable.
If you're travelling within Canada, SMS or texting isn't "long-distance."
Texting to the US has a different rate, and international texting does as well. As does texting back to Canada from there.
If you have access to wifi,* there are a slew of free or near-free ($0.99) texting apps, like Whatsapp, TextPlus, etc., that use data but act like SMS, and most can include media such as photos as well.
*Those apps will work on cellular data as well, but the cool thing is they work on wifi.