I'm going to take days off work and not tell my wife
Is there something you need to keep from your wife?
I need to take some time away from her for a while.
Taking days off work is fine when you need to but it's not okay to secretly get away from your wife.  If something is wrong in your relationship you should really tell her so you can work it out. She'd probably let you get away, but just distancing yourself without warning is going to cause more problems, especially if she finds out.
Nah, she's a dumb bitch and I want to fuck around on her.
It sounds like you are unhappy in your relationship, but what you said implied that you are going to be unfaithful while you are away.  I have to warn against this, as it is a breach of trust.  If you are truly dissatisfied with your marriage, your wife deserves to hear the truth, and you can both work it out.