First and foremost...Congratulations on your retirement, and I doubt you'll ever regret your decision to move to Thailand.
I think your choice of a Dongtan seaside condo is an excellent one.
I don't think Bang Saray would be a good fit for any retired farang unless he had a partner. There's a healthy expat community here but no gay bars - and I think a single gay person would be much happier in Pattaya closer to the bars and nightlife.
I zoom around the bay on my motorbike about once a week in the morning hours to hook up with friends in Pattaya. There are buses and mini vans that run 24/7 between PTY and Bang Saray but I prefer driving myself.
I have a Thai partner who I adore...have no interest in playing money-boy games anymore...totally at home in Bang Saray...clean air...lots of fun recreation...great beach for swimming....and it's only 25 minutes away from the flashing lights of Pattaya.
Good luck...and get ready to kick your shoes off and start acting like a crazy teenager again. That's what keeps us young over here.
Cheers