Have been to all but Labrador. The only ferry you absolutely need is from Nova Scotia to Newfoundland. The rest can be accessed by land, including PEI which has been accessible by bridge for some time now. If you want to take ferries you can take ferries out of Bar Harbor, ME to Yarmouth, NS, from Portland, ME to PEI, and Sydney, NS to Port-aux-Basques or Argentia, NFLD. The ferry to PAB is a 7 hour crossing while the one to Argentia is 16 hours. I'd take the day sail to PAB but it all depends on where you want to be in NFLD. It will also depend on whether or not you are prone to sea sickness as they do traverse open water. In any case make a back-up plan. Our last attempt to get to Newfoundland ended in NS due to bad weather that hung around for a few days.
If you choose to drive to NB I would go up 95 to Bangor, ME, then hook over to Rt. 9 (use your GPS but I think it's 395 to 46). That will connect you with Rt. 1 and you can follow the signs to Calais. From there it's pretty much up to you as to what route to take depending on what you want to see. Calais has the amenities you will need to stock up if you need to before you cross the border.
I may not have gone where I intended to go, but I think I have ended up where I needed to be
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[purple]RV-less for now but our spirits are still on the open road. [/purple]