For me, the first sounds rather formal and the second might be what you would casually say to someone as you left them the day before the meeting. "Right, I'm off now. I'll be seeing you tomorrow". However, "I'll see you tomorrow" would sound more natural in that scenario if an arrangement to meet has already been made or if, for example, the two people work together and one is simply stating a fact, that he will see the other in the office.
I would find "I'll be seeing you" better but of course that means "at some unspecified time in the future".
Noppanat - your signature line says you are an English teacher but:
1 - Your member profile does not say that.
2 - You have a spelling error in your signature line. You have put "form" instead of "from".