I am currently looking at combining MRU with South Africa (flying into JNB going to a game reserve then MRU then back to LHR). The main reason why this is an option is that I think 2 weeks on Mauritius is a bit too long. It is easy enough to get around the island, last time I hired a car for a few days. With regard to the inflight service I don't recall it being any different to that on flights to say LAX, SFO or BKK in F. The lack of jet lag and a daytime return flight mean you have a nice opportunity to enjoy the F service to the max
Between the two I prefer Samui and Phuket over Mauritius, but I'll be doing them in April

Of course the weather in Samui during July and August will be hot but there is also a fair bit of rain around.
On the weather front an expected 25C is alright with me ^