I have done the shark dives out of Pacific Harbour twice - once in 2006 with Beqa Adventure Divers (aka BAD) and again in 2012 with Aquatrek. Both were good so I would be hard-pressed to recommend one over the other. They each do their shark feeding dives from separate locations, maybe so as to avoid conflicts. But it is a similar set up, with a feeder in the middle and divers to each side set back a few feet with a wall at their back.
I also recall, but can't vouch that Aquatrek still does this, that if you had a large housed camera to protect yourself with, and if you were willing, you could be among divers that line in the form of a "U" with the feeder let's say at the bottom of the U. From these positions on the U, you could have sharks a lot closer for up-close shots, since they could be swimming by from behind on their way to the feeder. At times this was a bit intimidating - especially when a 10-ft bull zipped by without your having seen it.
Assuming that you do the 2-tank shark dives with either operator, and assuming that things have not changed much, the first dive is down to about 90 feet, and the second is shallower. With BAD we saw tigers on the deep dives but not on the shallow ones. With Aquatrek we didn't see any tigers, but as they say, it is an ocean so it is a matter of how lucky you are.
Again, my info is 10 years old, so do check them out. While both of them used to offer pick-ups from wherever you were staying in Pacific Harbour, BAD was up a hill and at least 20 minutes walk from town, whereas Aquatrek was right off the main East-West highway that connects Nadi with Suva. At least to me, staying closer to town was more convenient in terms of options for lodging and eating.
When I dove with Aquatrek, I stayed at the Pearl Resort in Pacific Harbour. It was close enough that I walked it everyday. It is not inexpensive, but if you can afford Shangri-La, I think that you can afford the Pearl. For other options, I would ask the dive operator that you decide to book with.
There is also Beqa Lagoon Resort on the island of Beqa, offshore from Pacific Harbour. They also offer a shark dive.
As to what to do on the other day, if I am given two days to dive, you better believe that I will be diving. Even if you cannot or won't do back-to-back shark dive days, Fiji has gorgeous soft corals.
Lastly, there is/was a bus that runs from Nadi to Pacific Harbour and on back and forth. It is quite comfortable and realtively inexpensive - a decent alternative to a private shuttle.
Good luck.
Manuel
