Love heights? SKY TREE AND TOKYO TOWER!
One of my favorite dates was going to Sky Tree and Tokyo Tower. These are easily accessible places with beautiful views. I recommend you to go to Sky Tree during the day (much better if you go up on a clear day) and enjoy the day view of the surrounding area from a bird's eye point of view. At night, you should visit Tokyo Tower and enjoy the night view of Tokyo and other areas. It is even better if you go to the cafe (after walking around Tokyo Tower), because you can enjoy the breathtaking view of Tokyo at night while enjoying a cup of tea or coffee. Tokyo Tower is also a good place to end up, because there are many restaurants that you may want to eat at after a romantic day in Tokyo.