Family vacay mid June - what does one wear that time of year?
During the day shorts and t shirts will be fine. After sunset you may need a light weight long sleeve top if you are sitting outside. Also good to be a bit more covered up in the evenings as the mozzies come out to play then.
I haven't stayed there so can't give personal opinion. Check their website for correct info. Most hotels require men to wear closed shoes and trainers are usually accepted.