We went last October - 21st to beginning of November. The weather the whole time was BEAUTIFUL - blue skies, no rain and daytime temperatures around mid eighties.
In comparison, in the evenings it did get a bit chilly occasionally especially in the pool - small quieter pools we found to be warmer than the main pool. I have never been in Spring though and I don't know how the temeperatures compare.
We usually go in the summer and were going again this July - but have had to book a short trip in October as well - it was so great (and you have the Food and Wine and the Halloween party (not just for kids either!) You'll love it.