Here is the situation
I am my own boss, and I want to take some vacation next week
What will I say:
"I am taking next week off" or "I am going to take next week off"
I think the second one is better because as I am my own boss it is not an arrangement with somebody else I am only involved in that decision and it is only an intention .
Now imagine that I already booked a hotel for this vacation , I will say "I am taking the next week off"