Translation:Tomorrow we are going to go to my sister's house.
From the English standpoint, the "go to" is superfluous. It is like saying I fell off of the building. "Fell off" is sufficient to make the point. The extra "of" is not required and can be considered noise. It seems that saying "going to my sisters house" is sufficient and the "go to" would be excessive and unnecessary to make the point. Unless, like mentioned above, "we're going all the way to sis." In that case it would denote that the journey itself held particular importance. To me this would imply that going all the way to your sister's house is a feat or a rare occurrence. Other wise I would simply omit the "go to." I hope that makes sense.