Selecting and Planting Bare Root Trees
Choosing fruit tree varieties
The key factor to look for is the minimum number of "chill hours" the variety requires. Simplistically, this is the number of hours in the winter below 45ºF required for good bloom and fruit set. If you do a computer search on "chill hours" you can find an average for your zip-code, or a map, etc., but, in Sonoma you will need to use that as a guide as we have many small microclimates within a zip-code. For stone fruit choosing the right chill factor is very important; apples and pears seem to be more tolerant of fewer chill hours than their ideal if you are of a mind to experiment. The chill requirement should be listed in the nursery's catalog and on the label of each individual tree.
Selecting a bare root tree
Look for trees with a trunk diameter of 1/2" to 5/8", with roots that are distributed around the trunk enough that it will be anchored on all sides when you plant it. The roots should be in a moist environment and the wood should look alive and healthy with visible, dormant, buds. Keep in mind that you will prune the trunk between 24" and 30" above the root flare when you plant it.
You will need to decide whether or not to use a gopher basket. The arguments against are that it can cause the roots to circle in on themselves and become "root bound", and any roots going out through the basket holes are potential gopher food anyway. The arguments for are peace of mind if your gopher population is significant, and you will not be as compelled to monitor for gophers and trap them.
Planting your bare root tree
Here is a great general article on evaluating your soil type to determine how to plant your new tree, and how to properly care for it if you have to delay planting for a few days: Bare Root Fruit Trees
If your planting site has any drainage issues, consider planting your trees on mounds rather than in holes. Do read this excellent article: Planting Bare Root Fruit Trees which shows mound planting, and covers watering, staking, and initial pruning.
Finally: don't forget to paint the trunk with a mixture of 1 part white latex paint to 1 part water. It will protect your young tree from sunburn and some insect pests.