Lay out all the cards on the table (or the floor in the middle of your classroom) so that all the students have easy access to them.
Ask your students to select 1 to 5 cards (the number will depend on the total number of students in class) that seem to represent what would be the most enjoyable vacation experience for them.
Your students' task is to describe a fantasy vacation illustrated with the pictures. Allow a couple of minutes to prepare: students might find taking notes or jotting down some expressions useful. Why not use it for dictionary work as well? 😉
Prompt your students to use present or future tenses, or possibly the Second Conditional, depending on what grammar you want them to practice.
Hint: My fantasy vacation is a perfect non-prep speaking activity, but it can easily become a writing activity as well.