あした is normally used by itself or with は. に sounds strange, but it's probably possible. For にちようび, all three are possible depending on the tone and the focus. Without a particle you would normally put a comma after にちようび. は and に sound best, though. You can also say "にちようびには", for example if you want to say that you're going somewhere on SUNDAY but not some other day. When you put は after, you put the word before it in focus. So the sense of "あした" is stronger when you say "あしたは" instead of just "あした".