Gosh, lots of "helpful" replies so far. I think people are getting a little to chummy on the board here.
I'd suggest checking out the Cabot Trail, which is about 300 km (3 hours highway driving) from Halifax, though you could split it up. The Cabot trail is beautiful, and there are lots of activities (including whale watching) in the area.
I also like St. John, New Brunswick, which has the "reversing falls" - basically the tidal changes make the river change direction depending on the time of the day.
Never been to Halifax, but I hear it's cool - lots of young people and bars and restaurants and such. PEI is also supposed to be interesting - if you like beaches or golf it would be a good idea.
This isn't a bad itinerary I just found: 7 day trip. You get to see most the sites, and you could probably stretch it out a bit more seeing as you have an extra week on top of that.
[ Edit: Fixed link ]
Actually, we probably have close to about two weeks. Do you think a trip to Newfoundland would be possible as well? I heard it's more quiet en beautiful but don't know about the prices of the ferry etc. Do I have to prebook the ferry?
Thanks again, Michael.
I only took the ferry to Newfoundland once - and that was when I was 10 so I don't have much information on the details. I do recall that it was a LONG trip - 8 hours.
Marine Atlantic manages the ferry, and has rates, schedules and you can make reservations there. Looks like the ferry is faster than when I went - 5.5 hours for day crossings.
I concur about the Cabot Trail, great. I like Cape Bretton Island off NE end of Nova Scotia (connected by bridge). Very bucolic.
Make sure you catch the tidal change along the Bay of Fundy. The world's highest tides occur here ranging from 30-45 feet (10-15 meters).
After living in Maine for years, I also recommend that you keep your eyes peeled for Moose. They love to get onto the roadways to get away from the bugs a bit. Unfortunately their eyes don't reflect headlights like a deer so they are difficult to see at night. They can cause massive damage to a vehicle, more so than a deer (Bulls can weight upwards of 1500 lbs, and cows close to 1000). Luckily they are not as numerous as the deer.