Best beach near Bangkok

Hello! I’ll be staying in Bangkok for a month and would like to plan a beach getaway one weekend.

From what I understand, there aren’t too many options nearby. Most of the good spots require flights.

I’ve read about Koh Kharm, but it’s not clear you can spend then night?

What are your favourite beaches near Bangkok?

Is there anywhere you’d recommend for 2-3 nights?

Thanks!