We have been to Merville Beach 6 times. Within walking distance to Grand Baie, 10 - 15 mins, with lots of pubs and entertainment.
If you plan to go there, try to book a superior room in the Garden court. Bit more expensive than standard room, but it is definately worth while.
Hotel staff very friendly - bar staff and boathouse crew.
Hope this helps.
Enjoy your holiday!