Booking accommodation in Langkawi and Penang for the year-end holidays

Hello, I’ll be in Malaysia with my wife, mainly in Langkawi and Penang for Christmas and New Year’s at the end of 2026. If you’ve had the experience—and since I’ve read (though it’s not very clear) that these two islands get quite crowded during this period—would you recommend booking accommodation well in advance, or is it easy to find something on the spot? Hotels or Airbnb? Do you have any great tips for accommodation or any practical info to share? We’ll be staying 5 to 7 days on each island. Thanks in advance for your replies