Very popular route. Most follow Panama to Marquesas, Tahiti, Rarotonga, Aitutaki, Palmerston, Niue, Tonga, Fiji, Vanuatu, then do the Bundenburg rally. Optional stops are usually Niue, Palmerston, Aitutaki. Some head to Samoa instead of Tonga. Late April, early May.
I recommend spending little time in Tahiti, but a ferry ride to Moorea for the day, Huahine for a few days, Bora Bora for a week if you time it for the Heiva Festival (free and better then Tahiti's performances), 10 days in the Marquesas, stopping in Rarotonga only to check in and take a 1 day trip around the island on a rental scooter, a couple of days in Aitutaki, a couple of weeks in Vava'u group of Tonga, stop at Niue (depending on weather)for a few days, you could spend years in Fiji or Vanuatu. You won't have time to do all the Tongan groups. Palmerston is also a nice stop for a couple of days.
Weather wasn't great this year in the entire South Pacific, including an early start to the cyclone season.
Take sailing guides and a South Pacific Lonely Planet.