This is from a 2024 article do things may have changed, but maybe a helpful starting point:
United
Aruba – 4 hours, 25 minutes (IAD-AUA)
Bahamas – 2 hours, 50 minutes (IAD-NAS)
Cancún – 3 hours, 50 minutes (IAD-CUN)
Cayman Islands – 3 hours, 40 minutes (IAD-GCM)
Dominican Republic – 3 hours, 45 minutes (IAD-PUJ)
Jamaica – 3 hours, 35 minutes (IAD-MBJ)
Puerto Rico – 3 hours, 46 minutes (IAD-SJU)
Saint Thomas – 3 hours, 55 minutes (IAD – STT)
Sint Maarten – 4 hours, 10 minutes (IAD-SXM)
Turks and Caicos – 3 hours, 15 minutes (IAD-PLS)
Southwest
Aruba – 4 hours, 30 minutes (BWI-AUA)
Bahamas – 2 hours, 40 minutes (BWI-NAS)
Cancún – 3 hours, 50 minutes (BWI-CUN)
Dominican Republic – 3 hours, 50-55 minutes (BWI-PUJ)
Jamaica – 3 hours, 30-40 minutes (BWI-MBJ)
Puerto Rico – 4 hours (BWI-SJU)
American Airlines
Bahamas – 2 hours, 47-59 minutes (DCA-NAS)
JetBlue
Puerto Rico – 3 hours, 43 minutes (DCA-SJU)
Frontier
Cancún – 4 hours, 5 minutes (BWI-CUN)
Puerto Rico – 3 hours, 58 minutes (BWI-SJU)
Spirit
Cancún – 3 hours, 54 minutes (BWI-CUN)
Puerto Rico – 3 hours, 52 minutes (BWI-SJU)
Read More:
https://www.islands.com/nonstop-flights-from-washington-dc-to-caribbean/