The scenery at Phi-Phi is amazing but I don't know if I would visit in late September due to the weather. Maya bay does not look quite the same on a cloudy day (I know I've done it). Its also a small island maybe not so great for a prolonged visit if the weather is a bit duff as many of the activities are sea based. However its a popular destination so you should find some life all year round as opposed to some of the less well known Thai destinations in green season.

Any other suggestions sunbear?

Er no not really...the places we go are pretty low key in high season so would be completly dead in low season. Did go to Koh Tao near Samui many years ago and that was nice but again you would need to investigate the weather patterns. THere is an advantage to the green season in that you can get some great hotel deals, and its the tropics so you should get some sun. We'ed maybe do Lanta again as we did not do it justice and we were going to re-visit Phi-Phi from there...we could see it from the hotel balcony.

Theres quite a bit of info here to help you make a choice on Phi-Phi
http://www.phiphi.phuket.com/info.htm

Would say Koh Phangan as I stayed there last July - late October / early November is rainy season though.

And like Koh Phi Phi it can get a bit lively, but normally away from the nicer resorts, so you need to journey into other places from your hotel. Pick carefully! Or goto Lombok!

Or goto Lombok!

Lombok? I know nothing about it. Please tell me more

Little island next to Bali (well it's not much smaller than Bali). Far less touristy. Only Singapore Airlines (using a subsiduary Silk Air) fly there internationally (although Garuda do fly to/from Kuala Lumpur) or you can take a 25 minute flight from Bali (or a speedboat which I hate).

Far fewer tourists than Bali, much nicer beaches, some really good snorkelling / diving (mainly off the Gili Islands), good weather at that time of the year, much better value for money than Bali, some lovely little hotels, a couple of busy areas (Sengiggi) which has some nightlife (I would love to know if the very corny Club Tropicana still exits!) and even a massive great big volcano (Rinjani) to climb if you are feeling a bit active.

You will pay more to get there, but less when you are there. By the sounds of it if you don't want to be somewhere too quiet stay on a) Gili Trawangan - although it might a but too party for you! or b) on the outskirts of Sengiggi - somewhere like Qunci Villa or Puri Mas where you won't get beach vendors etc.

Just a different option to consider! Bare in mind some doctors might recommend anti-malarials for Lombok. I won't disagree but i've never taken them for Lombok.

Ko Chang?? ..then to Ko Mak? ( that's where we're off to soon! LOL!)

Koh Chang / Koh Mak in late September is likely to be a bit damp unfortunately.

Southern Thailand is better at that time of year. But from late October - May, the Koh Chang, Koh Mak, Koh Kood area is well worth a visit. Far quieter than the islands in the south.

How about Koh Phangan? Will the weather be nice there at that time of year?