Nearly every garden I design has some of citrus tree in it and for good reason. Not only is the fruit wonderful, easy and tasty but citrus trees are evergreen, so they look great in the landscape all year round.
Many of the varieties are available in two different root stocks: dwarf (grows 8-10 feet tall) and regular (grows 20+ feet tall). Also, for the patient gardener, you can train your citrus into an espalier or have a professional, high-end gardener do this for you.
All citrus does well in full sun but here are some of our favorite varieties for Santa Clara, San Mateo and Alameda Counties:
Orange Trees

Cara Cara- Pink flesh, sweet and seedless

Navel Washington- Sweet, seedless winter ripening variety

Valencia- Harvested in June so they are very sweet, great for juicing

Moro Blood- Deep red coloration, almost purple-red. Very productive, early maturity, distinctive aroma, exotic berry-like flavor. Needs lots of heat

 Mandarin Trees

Satsuma ‘Owari- Hardiest tree of all mandarins. Fruit Ripens in November, December and is usually picked before the first frost. Seedless fruit peels easily

Golden Nugget- Seedless. The taste is extremely sweet when mature (March-May) with a very rich flavor, considered by professional taste panels to be one of the very best flavored citrus in the world.

Algerian Clementine- Ripens about a month after Satsuma, classic sweet/tart mandarin flavor. Few seeds.

 Lemon Trees

Eureka- A true lemon (not a hybrid like Meyer) has larger fruit bearing multiple crops per year, but the main season is late winter, spring, and early summer. Thornless.

Improved Meyer- Bears fruit year round and cold hardy. Can handle partial shade. Great for lemonade and cocktails

Variegated Pink – a mutation of ‘Eureka’ that has variegated (green-and-white striped) leaves and immature fruit striped green and cream, mature flesh is light pink plus the tree itself is smaller making it very garden-friendly.

 Lime Trees

Bearss- A tried and true lime that is great for cooking, drinks and cocktails

Mexican- If you like key lime pie, this is your tree

Palestine Sweet- Juicy yellow fruit with less sugar and acid than the Bearss Lime. With its mild flavor and few seeds, it makes a refreshing, cooling drink.

Kieffer- Their leaves, zest, and juice are used in Thai, Cambodian, and Indonesian cooking

Grapefruit Trees

Oroblanco- Sweet seedless fruit even in areas of low summer heat. Huge, intensely fragrant flowers and attractive glossy foliage.

Rio Red- Red-fleshed fruit that ripens in winter.  Wonderful for juice or eating fresh

Chandler pummel- Pink-fleshed fruit which are somewhat larger than standard grapefruit. Heavy producing in the right location, provided sufficient summer heat and frost protection

 Exotic Citrus Trees

Nagami Kumquat- The most widely available kumquat in North America. Olive size and shape, bright orange fruit.

Calamondin- Prolific fruit production. Zesty acid juice. Handsome compact habit making it great for containers

Buddha Hand Citron- Fruit forms finger-like sections resembling a human hand. It is much esteemed for its delicate lemon fragrance in China and Japan. Fruit has virtually no pulp, but can be sliced and candied in syrup. Not frost tolerant