This is a good activity to do before summer vacation when that is all students can think about, it gives them time to talk with their friends and come up with something they could do this summer while encouraging them to use English. I teach at a low level high school, with lots of students who also have low motivation, but this activity could be made more difficult by including target vocabulary or grammar within the students plans.
I give students a worksheet with an example plan I have come up with. I go over it with students and make sure they have a good understanding. I then explain that they will present these ideas before then end of class so they have roughly 25 minutes to write their own plans. I have them either work individually, in pairs or at the largest a group of three. I let students pick or let the JTE assign groups if necessary. I allow students to make both a realistic plan and outlandish ones if they wish and I encourage them to have something unique to their plan that other groups don’t have.
In their groups they have to come up with a plan that answers these questions in FULL sentences (I sometimes have to go around and remind students of this), with an emphasis on the 7th question:
1. Where is it?
What is the weather like?
What is the food?
What are the drinks?
Who will be invited?
What will you do?
Why is it unique?
While students are presenting their ideas to the rest of the class I am writing down the main points of their plan and what sets them apart from other groups and at the end of class if I have time I like to have students vote for the plan they would most like to actually go on.