Nobody likes a long airport layover, but for travelers who find themselves with lots of time on their hands at Reagan National Airport, Metro makes it possible to do a little sightseeing.

Hotels.com ranks Reagan National and San Diego International the best domestic airports for long layovers, where a $3 Metro trip in Washington or a $3 bus ride in San Diego can take travelers to the cities’ downtown areas within 15 minutes.

Hotels.com’s Airport Transportation Insider report looked at transit options from 29 major airports around the world in the most popular international and domestic destinations.

Among other takeaways:

• Most affordable airport taxis: Bogota and Bangkok, Beijing
• Mass transit options under $1: Mexico City , Bogota and Singapore
• Most affordable car service: Madrid, Rome, New York

Hotels.com also ranks Washington as the eighth most popular domestic destination for Americans.