As a Singaporean you can buy a 60 day tourist visa from the Thai Consulate in Singapore. That will give you 60 days entry. Then you can extend that once for a further 30 days and therefore you will have 90 days straight. After that you must leave. I did the 60 day TV Last year and extended it myself in person at my local immigration office and it cost me 1900 baht and half a day to do it. Good luck. 👍
actually Koh Samui is my second favourite place. It's just that I travel a lot and I like being near Suvarnabhumi Airport for my get aways. When I first started coming to Thailand I was a young guy, when you get older you tend to slow down and like things easy and nearby.
Pattaya for sure. Been coming to Thailand for 33 years and have seen 90% of the country but I chose to live/stay/visit Pattaya the most. The reason is that it has everything I need here. I walk everywhere, no need for transport. Everything is cheaper here compared to any of the islands. I can still rent a long term serviced room for 8,500 baht a month and can still buy a beer in a bar for 50 baht. Plenty of street food vendors and several decent restaurants around at reasonable prices. When I buy a whole fish dinner you pay a standard fixed price per whole fish, not like the swanky BS pay by gram rip off restaurants on the islands. And for exercise I have a 2 kilometre long promenade to walk on Everyday, no cars or motorcycles. I love Pattaya for these reasons.
There is only 1 rule when using wise to transfer to Thailand. That is not to look at the fees but to look at the nett result after fees. So far I can't find any transfer company that can do it better. By the way my country Australia shows fees of triple of USA fees yet I only pay $7.47 aud in fees for a $1,000 transfer. Anyhow the nett result after all fees and expenses is all that matters.
Last year I had a forced flight change and I was 24 hours overstay. No fine or problem, they gave me a 24 hours stamp and was allowed to leave without problem.