Melissa,
Welcome aboard! You will have a fantastic time on the PG. We just went in December and loved it. We are going back this December for an 11-night sailing. The food is very good, the staff is friendly and will take very good care of you. Be sure to eat dinner in La Veranda one night - the food was outstanding. We liked the Grill for dinner too, though reviews from others have been somewhat mixed. We will do both again.
You have already been given lots of good advice. There is 1 US-style electrical outlet so the suggestion to bring a small power strip is a good one if you have several electrical items to recharge. I took a pair of sweat pants for lounging in the room and didn't use them. I think I would have except that I fell asleep upon returning to the room each night. All that sun and fresh air! Here's a quick rundown of our excursions:
Raiatea - we did the Faaroa River trip which is part canoe and part 4x4. We liked this because you got to see the interior of the island, the river, and the coastline. No problems with queasiness in the 4x4 but the canoe is uncovered so sun protection is needed.
Tahaa - enjoy the full day at the motu. Very relaxing. We were on the second tender over (tried for the first but there was a long line, I think our only line of the week!) and the last tender back.
Bora Bora - the first day we did the Shark & Ray feeding tour. This was a blast, we had so much fun playing with the rays. Here we also had our best snorkeling of the week (Bora Bora Coral Garden). Second day we did the 4x4 which was great - lots of outstanding views. No queasiness on this one either, but definitely bumpy. We shopped a little in the village and went to the Bora Bora motu. As mentioned, this motu has much less to offer in terms of facilities, but is worth going to if you like the beach.
In Moorea, I was glad to have sneakers on the Trails of the Ancients as it rained while we were walking and was pretty muddy, and we needed to cross some small streams along the way. River sandals would be OK too, maybe better considering how wet it was! We also took Dr. Poole's dolphin excursion as mentioned above by Bill. We were lucky enough to have the opposite experience - we saw over 60 dolphins and I think it was the highlight of the week for me. The snorkeling on this trip was so-so, but seeing all the dolphins was outstanding.
If you have any more questions, ask away!
Dena