I would say that for a honeymoon, probably Victoria & Albert's would be the most romantic because it's very quiet and upscale. I've eaten there, and it was very good, but I personally enjoy California Grill and Jiko even more. Neither has quite the "fancy" experience, although they are still upscale restaurants, but I personally enjoy there food a little more. You can book your dinner around the fireworks at California Grill, and that is very romantic, and at Jiko it's pretty quiet and the food is so good with a fantastic wine list. Enjoy whatever you decide!