Leftover traveler's checks will never depreciate in value nor expire, so there's no reason to hold onto them until your next trip. Cashing your unused checks gives you access to the money right away.
Convert to Cash
Use the traveler's checks to make a purchase at any store where they are accepted and you will receive your change in cash. Most retail establishments accept traveler's checks. Alternatively, most banks will cash traveler's checks, however, you may be required to pay a service charge. Fees may vary per bank.
Deposit Without Fees
Avoid service fees by depositing the traveler's checks into your checking or savings account. Make the check payable to yourself and countersign the check in the presence of a teller. Most banks will post the deposit to your account by midnight of the same day; posting date will vary per financial institution.