Flight costs from $800 to $1000 if you are flying from Columbus. It is a little expensive but I think it is well worth it. You may be able to find cheaper flight If you find one on sale or they may be cheacher at different times of the year.
The Westin dawn beach resort and spa is one of the best hotels in st.martin. It has a great pool and is very nice. Also has a good beach with nice water.
Maho beach is a great place to spend the day in the sun and water. There are planes that fly right over the beach like in the to left picture. Another place to spend the day is Loterie farm. It is very relaxing and is a Nature sanctuary on 135 acres with hiking trails & zip lines. The last place that I would check out is the rhino safari. You pilot your own watercraft on an award winning guided snorkeling adventure. You ride on a two-man Rhino Rider that is lots of fun like in the picture above.