Almost every ESL textbook has a unit on Travel or Weather or Seasons. Here is an excellent "task-based" kind of activity that you can do with your students, which will fit into any of these units really well:
Put the students into groups of 4-6 (I do it randomly). The students are a tour company and the customers are my parents who are coming from Canada to Busan for a visit. I will show them a picture of my parents and explain about the kinds of things they like and don't like (example: they like walking around, and sightseeing as well as watching sports, but they hate seafood). Then, the students have to plan a 1-3 day tour (depending on the time for the activity/level of students) of Busan (or your city) for my parents.
I usually give them around 20-30 minutes for the task, and at the end they have to share their ideas with me and the class. I make a rule that 2-3 people should do the speaking, to give more students a chance to talk. I pick the top groups, based upon the following:
1. I think my parents would love the tour
2. They just speak, and don't read from a paper
3. Their presentation was convincing.
And of course, they get a little prize (one stamp as part of my reward system).
This could also be adapted into a more comprehensive task, such as making a brochure or promo video or something like that.