If you are at SLU airport hen none of them are far away and Halcyon would be closest at 10 minutes. The other two would each be about 20 or 25 minutes.
For the larger airport, UVF, to get to Sandals La Toc is about 1 hour 20 minutes, Halcyon 1 hour, 30 minutes and Grande, 1 hour, 40 minutes. The times are dependent on traffic in and around Castries.