One of the easiest type of transportation from BKK to Koh Phanganwould be to get yourself a joint ticket from Songserm Travel Center for ferry and speed boats, buses, railway, airplanes to Koh Phangan. Or you can get an 1 hr. flight operated by Bangkok Airways 6 times a day from BKK to Koh Samuiand get the catamaran boat to Phangan.
The weathercondition in Thailandcan be very tropic, hot and damp. Most of the time weatherseason are designed by monsoons that create 3 distinguishable climateseasons in northern regions of Thailandand two other seasons in Southern Siam. The south-west monsoon approx May to October is warm and many clouds, but in northeast monsoon in Nov to March is rainless and comparatively low temperature.
A good alternative for staying on the island could be Phrueksa BeachResort, because it's perfect for various types of tourists. It's ideal for newly-married couples on honeymoon and small families and a group of friends as well.