I was thinking in another day that one of the differences between みたい and そう (meaning "it seems") is that the first can be bound to a sentence in the past while the second forces the verb of the sentence to be always in the ます stem.
 I think that difference allow みたい to create sentences like "昨日、雨が降ったみたいでした" meaning "yesterday it seemed like it had rained" (I don't know if the sentence or translation is right). Is that right?