The announcement is a place to get in touch with your clients through public notices. These notices can include offers, news, updates &, etc. It is important to set a correct date for the start date and expiration date so the offer would be shown at that range only and be expired after afterwhile.
Coupons are a great marketing tool to help with user retention rates. Users can keep them to get discounts on their trips. Coupons just like promotions have an expiry date and they won't be available to users to use after the expiry date. Customers can enter the coupon code during the trip to get the discount.