Good luck with your trip Barry.
Here is probabably the best link on the web for tides.
Tide Location Selection for the Florida Keys Area
If you will be wading for bones, I would suggest oceanside flats very late in the evening, particularly as the tide is coming in on calm days. This tide will also provide very good daybreak fishing as well.
Long Key can be a good spot, towards the NE end on an outgoing tide when there is a pretty good flow, out from the lake. There is a boardwalk leading down to that area with a little bridge over the "brook". I have seen large bones in the past swimming under that bridge.
Wading there is extremely nasty, however, due to the silt buildup from the lake. From there all the way up and through the campground can be very good if camper commotion is not too vigorous. The wading gets very good in the campground area, though there are potholes in many places from those damn low tide treasure hunters that dont fill in their holes.
Keys bones are much spookier and more difficult to catch than carribean ones. They are also bigger. If you are fishing near dark, use larger flies than during the daylight. If fishing weeds in less than knee deep water, give a long slow strip as the fly lands so the fish see the fly, then let the fly settle. Stripping in bay grass is not a good idea, especially with fluorocarbon, as the leader moves the grass ahead of the fly.
There are rays everywhere down here but pose no problem. In fact, the more you see on the flats, the better the chances that bones will show up. Just wear wading shoes and shuffle along. If you decide to go for the muck at the long key flowage area, you might even want lace up, over the ankles, wading shoes as the rubber ones can get sucked off your feet.
Use darker flies over grass and lighter ones over lighter bottoms. If you are still checking this thread, let me know when you are coming.
Have a great trip.