I went once from
St Lucia to Bequia on the windward side of St Vincent, and I was a bit disappointed--it may have been just that day, but the winds were lighter than I expected and the waves reflect of the island, making it a sloppy sail. I've gone on the leeward side at least half a dozen times, and prefer it. You may have to
motor for an hour or two, but the lee is a nice smooth place to have lunch.
The channel between Bequia and St Vincent has a tidal current, but the west-setting flood is about 2kn while the ebb is about 1 kn, and better near the shorelines. The racers in the round Bequia
regatta always tack pretty close to the shoreline up to Man Point, not just for the current relief, but because the wind bends around the point.
I stopped for the night once in the lee of St Vincent (Walliabou), but will never make that mistake again. Leave Bequia early, and keep going to
St Lucia. As mentioned, motorsail close inshore up the northern end of St Vincent until the wind and waves fill in, then sail out into the channel with a double reef.