One of the most common problem that students have before come to Vancouver is, when they have to choose an English school. In order to help them, I will try to give them some advices.
First, if I were them, I would try to find a small school (that mean with few students), so it doesn't mean a school with a few classrooms an a lot of students ( specially in the summer season).
Second, If you really wanna learn English, try to ask for a school focused on the Japanese market because if at the end of your course you are able to understand the rookies Japaneses , you are going to able to understand any other non-native speaker. Nonetheless, if you follow these advices, maybe at the end of your English course you will learn more Japanese than English. Who knows? Could this English course be the first step to go to Japan to study Japanese? In that case, just do it.