USDA Hardiness Zones are determined based on the average coldest temperature for each region. Plants are therefore listed in zones that do not get colder than the lowest temperature they can tolerate. Zone 8, which is further broken down into 8a and 8b, includes those areas of the United States that have low temperatures from 10 to 20 degrees F. This represents quite a variable list and includes Las Vegas, Portland, Seattle, parts of Georgia, Texas Florida, California, and others. Many plants are hardy to USDA Zone 8 and lots of those are fruit trees.
Pear trees thrive in a slightly acid soil so you may need to run some soil tests prior to planting your pear tree. They also require full sun all day and careful pruning every year. The pear tree can live and bear fruit for up to 75 years so it is worth it to pay close attention to its needs. Varieties that grow well in Zone 8 include the Bartlett, D'Anjou and Kieffer.
A mature cherry tree, one that has reached four years old, can bear 30 to 50 quarts of fruit per season. That's a lot of tarts and pies and gifts to the neighbors. Cherry trees need sunshine and slightly acidic soil. The Bing variety grows well in Zone 8 but you should also plant the Black Tartarian or the Rainier for cross-pollination.
Many varieties of apples can be grown in Zone 8, including Golden Delicious, Gravenstein, and Granny Smith. If you plan to grow an apple tree keep in mind that it will need full sun, all day and lots of water while it is young. Even with the best care it will take several years to go from a seedling to a mature, producing tree.