Knowing what you need in the way of a boat is a primary concern. If you're going it alone, then don't get too much boat and if you're going with friends, make sure you've got enough room to move and get out of each other's way.
Also make sure you get the right style of boat. A small, fast yacht is not going to be ideal if you're taking people who aren't used to sailing yachts - and more importantly living aboard them.
Consider a catamaran, either a sailing cat or a power cat, which are becoming increasingly popular.
A sailing cat is a great compromise. The sailors can have a bit of fun sailing, especially downwind, while the not-so-keen can still enjoy a chardy or a beer without it spilling. They generally come with a couple of nice diesels so they're great upwind too.
The big advantage of cats is room. A 38ft cat can comfortably handle a group of 6–8 for a charter of 5–7 days. They offer four staterooms, a minimum of two full heads with shower stalls, and voluminous entertaining areas both inside and out. There's plenty of room for lazing about on the foredeck and it's comfortable whether you're at rest or making way.
Cats are easy to handle too with twin engines and broad beams they can virtually spin on their own length. They have the added benefit of a shallow draft which means that you shouldn't run foul of the numerous bommies and shoals in the area and you can sneak up close to beaches as well.
Most big charter companies have yachts from about 33ft to 50ft - which will cover your needs, from a two person holiday to a party of eight.
Obviously the prices vary according to the size of the boat and the season, but it's not uncommon to be able to get a yacht for around $200 to $400 per night per couple if you share. That's comparable, and often cheaper, than staying on shore.
WHAT DO YOU GET?
Most boats are fully self sufficient. In the past, I've made the mistake of taking far too much gear with me.
Towels, linen, all kitchenware, cooking and cleaning gear, even down to the salt and pepper and the all-important corkscrew is supplied. All you really need is a couple of pairs of shorts and your teddy bear and you're right.
Of course, all boats get a rigid inflatable dinghy with outboard so you can go exploring the coves and inlets and even do some bush walking to stretch your legs.