Stays, flights, car hire and tours. Codes in this category are limited by travel date rather than by booking date, which is the opposite of how most retail coupons work — a code that expires next week may still cover a trip six months out.
Read the cancellation terms alongside the discount. Discounted rates are frequently non-refundable, and the difference between a flexible and a non-refundable rate is often larger than the coupon itself.
Loyalty programs are worth more than codes here. Genius-style tiers and member rates apply automatically once you are signed in, and they generally cannot be combined with a promotional code, so compare the two before booking.