It sounds bad, but I'm planning a two week long trip out of state to visit family without discussing it with my wife.
That's odd, how will your wife feel when you go?
She doesn't like it because she will miss me
It is ok to want to visit people alone sometimes. You should talk to her about it so she doesn't suspect you are cheating.
I don't want to make a deal out of it. I want it to be a surprise.
Sometimes surprises are good, but in this case you might want to tell your wife your leaving alone to avoid unnecessary drama. Keeping secrets like this from your partner could have a negative impact on your relationship.