I'll preface this by saying Tahiti is one of my favorite places to charter (4 times) and the Admiral & I have made numerous trips to and were married in Fiji.

Both will make an unforgetable trip. They both have great high end accomodations.

Fiji has a greater range from packpackers to Forbes, with lots more adventures, diving, hiking, water falls, river rafting etc. Not everyone's idea of a honeymoon trip!

Tahiti is very expensive and Bora Bora has aquired a bit of a negative "Honeymoon mill" rap. The iles sous le vent are truly some of the most beautiful islands anywhere. Tahiti is also hours closer 7.5 vs 10.5 and an easy flight from LAX (only 2 hour time change, arrive same day).

Great idea on the Crewed Charter, but why not do both? Few days in the obigatory Bora Bora overwater bungalow then on to the charter, to experience a beauty no package honeymooners will even know exists.