Preparing the garden to leave for vacation is a little easier this year since everything outside is already watered and beds are unlikely need more.
If someone is coming over to check on the potted plants for you - they dry out in a couple of days even if the ground is a sponge - gather them together under a tree or on a hard surface and definitely near a water source. Move all hanging baskets to one location so none will be missed by the good Samaritan who is caring for them.
To the extent possible, put houseplants in the bathtub or on a kitchen counter where they will be noticed. For some reason one plant is always missed if visitors are left to their own devices.
Add to your planning list a thorough bug and disease check. Look under the leaves of plants that tend to be vulnerable, like new trees and shrubs or pot bound houseplants.
Since you won't be home to watch them for damage, use a gentle spray for insect and fungus protection. Safer Soap is great for many plant problems and rarely burns the leaves.
Invite your plant-sitter to pick produce that matures while you are gone to keep the trees, vines and bushes producing and healthy in your absence.