Fishing has been good around GI. Just got back to Houston after 2 weeks there. A few thoughts for your consideration:
1) The marinas can be good sources of info and ask when you buy some bait or supplies from them. Always worth a shot.
2) The last several trips we have been doing well on windblown points on an incoming tide just north of Grand Isle. Any of the little islands behind GI will have fish, but many see a fair amount of pressure. We run and gun and cover several spots each trip. Sometimes the first couple have the fish, if not move on. Have a gameplan to try several spots. We have done better near areas with oysters, but not critical. I also throw artificials 95% of the time and done well with Vudu shrimp under a popping cork, Egret Wedgetail or Matrix shad type baits on jig heads and always have a top water tied on.
3) There are known 'community holes' near the marinas that get covered up pretty quick, like the Caminada pass rocks. I fish it during the week and try to hit it when no other boats are there - rare these days - might be worth a quick look. Same thing around Sand Dollar on the east end of the island. There are rock jetty points close by and if the Gulf is calm the rocks by the Fort or near the State park can be good. Remember, there are rocks under the water that may not be visible around the visible rock piles/jetties, so respect that and imagine the line of rocks continuing a bit underwater. Run and gun those areas as they may not be on rock pile A, but are stacked up on rock pile D.
4) If you will be there a few days consider hiring a local guide for one of those days. They know the area and the bite pattern and a good source of info for a few areas and techniques. They will help you - just tell them what you want to do and respect their areas if you see them again in any of those spots. I would call Capt Danny Wray at Calmwater Charters. Easy going well respected guide.
http://www.calmwatercharters.net/#!f...charters/c24i2
Good luck and have some fun on Grand Isle.