I live in Newfoundland, I would recommend the following:
Icebergs are starting to come in, go on an iceberg tour (http://icebergquest.com/
). Also check out: http://www.icebergfinder.com/
The drive through Humber Valley (near Corner Brook) is beautiful. There are really nice lodges you can rent for a somewhat reasonable rate. (Humber Valley Resort).
Gros Morne national park is nice although I've never been! Google it.
Terra Nova National Park is also very nice.
Salmon Fest is in the summer time. (http://www.salmonfestival.com/
Lots and lots of good restaurants in St. John's, too many to list.
St. Pierre could be nice although I've never been.
There's a nice historical site called "Castle Hill" out near a town called Placentia. I think it's near where you will get the ferry for St. Pierre so might be worth a day trip if you're into that sorta thing.
Stan Cook Sea Kayaking is really fun.
Local delicacy is fish and chips, my favorite place is called "By the Bay" near Portugal Cove. Another great place is called "The Captain's Table" which you would pass on your way back from Sea Kayaking. People will try to tell you to go to Ches' Fish and Chips, they've been around for a very long time, but they're not the best in my opinion..
Newfoundland has some nice local beers, Quidi Vidi Ice Berg Beer is very good. They also make a IPA which is pretty good. Yellow Belly Brewery and Pub is on Water Street in St. John's, definitely go there for a meal if you're in town.
Night life is great on George Street.
There are lots of nice shops and boutiques on Water Street in St. John's.
Go visit Signal Hill and Cape Spear, can probably do both all in one day. Even if you only go for 30 minutes you can get some really nice photos. Stay all day if you want to hike around the trails.
If you're into Hiking the East Coast Trail is really excellent. Maps can be obtained from "The Outfitters" on Water Street.
Most of the stuff I've been listing is on or near the Avalon peninsula, but if you google Corner Brook tourism I'm sure you'll find more to do over on the west coast.
If you have any other questions let me know I can try to help!