Anyone ever been to Thailand in August (Rainy Season)

I have, twice. Rainy season in Thailand is nothing like what you think. You may get a huge downpour for about 10 mins and then it stops the sun comes out and within 5 mins because of the heat it's as if it never rained. Phuket is beautiful also, if you can go and see Phuket Fanta-sea it's bizarre but very good. I'd also highly recommend the elephant trekking and you can also enter the enclosure with tigers if you're feeling brave. Make sure to get your vaccines from the docs before you go and take plenty of mozzy spray. Also don't eat any of the fresh fruit or you will end up with the runs as they wash it in tap water. (edited)

Yeah , we usually go just after August in September, I get why you might be worried....but when it rains in Thailand it's very different from the UK , it can usually be very hard rain for 30 mins , with streets flooded and yet in an hour the roads and everything is back to normal....
I've been to several places in Thailand and although I like Phuket I personally think koh samui is Much MUCH nicer , better beaches and more relaxing , we went last year and did both and koh samui was a clear favourite out of the 2 ....if you would like the name of a very good but expensive hotel let me know as this hotel beat every 4&5 * hotel I've stayed in....it was stunning