For a slow boat, with a nervous wife, the best move IMO, is to go down to Lake Worth and cross straight to West End. Then go on to Great Sale or Double Breasted, then Allen's PCola, then GTC. Much easier to take it in chunks.
For us at 15 knots and with many crossings under our belt, we go straight from St. Lucie to White Sand Ridge then on to Grand in one day. We clear in Grand spend a night or two then take our time working South.
On the way back we go down to West End, spend the night, fuel up (Cheapest fuel in the area) and use the stream to push us north to St. Lucie Inlet. It takes the same amount of time as going from West End to Lake Worth.
The banks West of Grand can get pretty darn snotty. Sometimes worse then the stream. It's shallow but still open water. Probably not the best move for a nervous first timer.