The correct choice is Option 1: 'That's true. Where would you like to go?' The speaker is expressing a hypothetical desire to travel ('旅行したいなあ'). A conversational and cooperative response is to agree ('そうですね') and expand the topic with a question ('どこがいいですか' - Where would be good?). Option 2 ('旅行は疲れました' - Traveling was tiring) uses past tense abruptly and shuts down the topic. Option 3 ('休みは長いです' - The vacation is long) is a literal statement that doesn't fit the flow of sharing vacation dreams.