Kat, it kind of also depends of what you want to do, do you want to relax? or do you want to visit different sites and learn about history? If you go to Europe (I wouldn't recommend London for a honeymoon) you'll have to be on the go all the time because you'll want to see everything (Venice is stunning, but I would go to Rome and Florence). I've been to the South Pacific and it was spectacular! Bora Bora was my favorite of the islands. We stayed at Le Meridien and it was out of this world, I like the location which is on one of the Motus. Motus are a group of islands that surround the main island. Le Meridien and all of the resorts on the Motus provide water taxi transportation to the island. Also, Le Meridien is right next to the St. Regis which looks absolutely devine! They have all overwater bungalows with their own private pools.
I would recommend if you visit other islands besides Bora Bora, I also went to Moorea and didn't really like it. I recommend Roatonga.
I hope this helps, it's absolutely gorgeous there and you will have a very awesome and relaxing honeymoon.