If I am going somewhere for a long weekend, I want a direct flight. That is typically a bigger priority than the destination or hotel. You don't want to get stuck in Houston or Newark, for example, waiting for a connecting flight while seeing your precious time tick away.
So if you use that criteria, places like St Kitts or Curacao (both of which we have been to and enjoyed the Marriott properties) aren't really suitable. I would go to either of them again, as long as I had 5 days or more.
We did a long weekend in San Juan this winter and it worked out well. We stayed at the Courtyard Isla Verde, which was quite nice and plenty of places to walk to for breakfast/dinner/drinks. Loved using the free bikes for guests in the morning. And we got upgraded to oceanfront from ocean view.
We've stayed at the CasaMagna in Cancun and loved the beach there - plus we got a beautiful top floor corner room oceanfront upgrade. There are a few places within walking distance, but the bus system in Cancun is easy and cheap.
We really like the Puerto Vallarta CasaMagna, but not sure if there is a daily nonstop flight from ORD. The beach isn't that great for swimming but the pool is lovely, the service is awesome and we just love the PV vibe.
Of course, as others have mentioned, Florida is always an option. Plenty of great beach destinations, including the South Beach area where you can take a taxi/Uber from the airport and then walk everywhere at night.