There are as many different types of charter yachts available as there are locations in the world to charter them.  Charter yachts range in size, shape, length, and width.  Charter yachts range from powerboat monohull and multihull to sailing mono and multihull.  There are brand new high tech racing charter yachts and cruisers and there are old classic racers and cruisers.  There are older cruiser bareboat charter yachts which are cheaper to book than onshore accommodation. There are luxurious superyachts with crew that cater to every charter guest's whim and pleasure. These different types of charter yacht suit each particular purpose or each particular charter guest.

A sailing vacation aboard a cruising yacht is like no other. Go where you want, swim, snorkel, dive, read, sun-bathe, sail, eat, drink, and be exceedingly merry.  Such sailing tours are usually all planned just the way you want it. Yachts enhance your vacation with their comfort and privacy. If you decided for a yacht charter, you may choose from the several options:
Bareboat Yachts that you sail yourself (if qualified)
Fully Crewed Yachts with licensed captain and trained chef/hostess. 
Captain Only Yachts (if you would prefer to have an experienced and licensed seaman onboard for some or all of the duration of your stay) where you provision and prepare the meals.

Monohulls include schooners, sloops and ketches. Monohull yacht charter is great for adventure sailing or cruising. Although comfortable, monohulls don't tend to have as much interior and unused deck space as a catamarans.
Catamarans/Multi-hulls - catamaran yacht charter is great for stable and fast cruising. For a charter yacht of the same length, they have far more interior space. Catamarans have a low draught, allowing cruising in shallower waters.
Motor-sailers are predominantly monohulls. They have a large engine capacity, similar to some power boats. This allows great speed when under power. They also have the benefits of sail and wind power.
Both monohull and catamaran power boats provide extra space, comfort and luxury.  They also generally cruise faster than sailboats.

There is the big debate: which option to choose - a monohull yacht charter or a catamaran yacht charter.
There are many advantages why you should hire a catamaran rather than a monohull yacht or a caravan.
Catamaran Pros:
The catamaran will provide you with considerably more room than a monohull basically everywhere on the boat: in the cabins, in the salon and in the cockpit, the latter usually being huge, since it spans over both hulls. A typical 45 ft. cat will have 4 large staterooms, with queen-size beds, each with en-suite bathrooms, and a salon/cockpit combination capable to sit and entertain 20 people. A 38 to 42ft. will have 3 staterooms and 2/3 bathrooms. The cockpit and the salon are on the same level, which enhances the feeling of spaciousness. There is ample headroom everywhere. The foredeck also has a big net between the hulls, which makes a great sun bathing area. As a result of this roominess, a catamaran rarely feels crowded as it is relatively easy to get some seclusion and quietness from other members of the party.
Because of the cats layout configuration, you have full privacy in every room and you don't hear anything from one room to the other.
The other major fact is that a catamaran does not heel and does not roll at anchor. This usually makes seasickness a non-event. Incidentally, it makes it somewhat safer for kids running around.
A catamaran usually sails faster than a monohull on some point of sails (beam reach and downwind).
Cats have a shallow draft, allowing you more gunkholing than a monohull.

Catamaran Cons:
A hard-core monohull sailor once said: "When I sail a cat, it feels like I am driving my living room!" He meant that a cat does not convey the "real" feeling of sailing, with the "rail in the water" as they say. That is precisely because a cat does not heel, and a monohull does, sometimes a lot. So if you are in for hard, pure sailing, you will not get that felling on a cat. Only a monohull yacht charter will give you the full experience!
Lastly, a cat does not typically sail well upwind and needs a different technique for tacking and anchoring.
Conclusion: If you are bringing with you a party of first-time sailors, or older people, or people who could feel apprehensive at sea, you probably better choose a monohull yacht charter.