Bonaire is very laid back. Unless you are an avid snorkeler or a scuba diver that is about all there is to do. There is no comparison to SXM. Curacao is a more tourist attraction where you have the European influence of the Dutch. Very cosmopolitan, Safe, beaches have coral coast line but once you are in the water it is sandy bottom. Abundance of sea life, water clarity is unbelievable (same for Bonaire). Again, no comparison between the 2 islands and SXM but it is a different adventure and you may like it. We did.
Thanks for your input! As stated on the SXM board, we have (sadly) changed our original St. Maarten trip to Curacao for this October/November. While no place is St. Maarten in our minds, we are hoping to find some semblance of a beach vacation, while actively working to shake the sadness from our souls. We tried Aruba last year and didn't care for it. Curacao was recommended to us by several people, so we'll see how it goes.