We decided to go for Barbados in the end as couldn't get the Mauritius flights home before my children go back to school.
As mentioned above, we've been to Barbados in August before and we did have days where it rained, but it didn't stop play! If my girls were in the pool anyway then they might as well stay in it, the rain doesn't matter!
There is the risk in Barbados of bad weather - we were going to go one october but house sale fell through so we couldnt. It turned out the weather would have been terrible as it did get a tropical storm/ hurricane.
We had a great holiday in Mauritius in late July (children then 9 and 5), staying on the west side. Weather was really nice - warm but not too hot so we didn't have to worry about covering up or sun cream every 5 minutes. We had a hire car the whole time so could take trips to the safari park, sugar museum etc.
Trying to decide between the two, nice dilemma I know.
We went to Barbados 2 years ago and loved it, stayed at the Turtle Beach and would go back there. Went to Mauritius on honeymoon 10 years ago (it's our 10yr anniversary in September so it seems quite fitting to be returning there this year) and had a fab time, though as couldn't afford to stay where we did then. We've now got two children, they'll be 5 and 8 when we go.
So, which would you choose and why? I know August is winter in Mauritius but we'd be staying on the west coast which is gather is less windy and the weather is actually quite nice that time of year.