Sailing a dinghy will make you more aware of the interactions of boat, waves, and wind than a keelboat and you could some dinghy sailing for that purpose but it is unlikely to be a big deal in preparing you for extended cruising. What you could do is really pay attention to how your boat feels and experiment with adjusting your sails (eg traveller or outhaul) one thing at a time in consistent conditions to see what effect it has on boat speed, heeling, general feel of the boat - approach this very systematically and keep notes.
Don't know the curriculum of the courses in the US, others may comment on this. One other way to improve is to crew for people who are knowledgeable - for example, crew on a trip to or from Bermuda to get some offshore experience. Different skippers, different boats, lots to learn and you will get different takes on how to approach the whole experience - again keep notes.
Back in the water in Grenada - with new main and #2 and cockpit canvas (Santa came early). Will spend the winter and early spring in the Caribbean and then head to Bermuda and the northeast US. Still trying to decide if we will bring the boat to Canada, either in 2015 or 2016.