Some islands are far from each other and ferry costs adds up. But more importantly it's tricky to really find what u are looking for in an island.
Some want to party, some want the comforts of dining options, shopping etc. For me, I want remoteness. I don't want to be surrounded by tourists. I also wanted tome snorkeling actions and pretty, not polluted beaches. But of course the more remote you go, the more expensive everything gets.
You can google islands to see images but the reality is not aways matching what Google shows you. Also the days of cheap backpackers places are disappearing. All Of Asia is developing more upscale reports and even food is not as cheap anymore.
We visited ko Hong island as a day trip from ao nang beach which is near the major town of krabi. Even the not to big towns are super packed and just trashy with bars and rubbish. We lucked out with a bit of sun though the clouds with only pouring rain overnight and on the day of travel to the island of Ko lanta.
We had not idea a storm has been hitting further north. Ko lanta experienced no electricity which not only means no wifi but also no ATMs and no shower or running water at the bungalow. Very lucky compared to the other islands that experienced major floods for a second time during this not rainy season.
The strong winds knocked down some trees and sadly we couldn't visit a nations park nearby. At one beach I picked up about 100 lighters that got swept up during the storm.
Tourists feed the monkies that are by the roads and while walking on the street one monkey grabbed our bag that had snacks and drinks. He only got the almonds and an emergency c. It's so scary because they can bite you but so many tourists act so poorly with these wild animals.
The weather for better every day and we were able to hike to a bat cave. It was small and sadly no bats. This was on the way to a waterfall which was refreshing and not too cold but also not a big waterfall.
Pix of Ko Hong and ao nang https://goo.gl/photos/pVoWHV9MDGvCfgpX9
Pix of Ko lanta https://goo.gl/photos/DtSP31dBW1YVJaGx6