Silverskin garlic, often referred to as soft-neck garlic, stores incredibly well and is the type used for making garlic braids. During the growing season, this type of garlic will form flower heads which need to be cut off so they do not drain the resources of the bulb. Most rocambole-types have a very pungent, almost hot flavour and are often identified by the purplish tinge to their skin. Although this is a much more gourmet garlic, it does not store well, usually just a couple of months. The cloves of this garlic can weigh an ounce and will usually give up to 3 tablespoons of chopped garlic.
Elephant garlic is actually a member of the leek family and thus, has a much milder taste.
The bulbs of elephant garlic should be spaced farther apart, usually 10 inches, to give the plants enough room to grow. The best source of bulbs would be local growers who sell seed garlic at local markets. These varieties are well adapted to your growing conditions. A second best, or to get more variety, try mail-order catalogues such as Territorial Seeds or Garden City Seeds. The best selection I've seen by far, however, is Salt Spring Seeds.