I love plank cooking, I personally love the smell and taste of Cedar, as it is such a fragrant & spicy flavour. Cedar is especially good with fish such as salmon Trout, or any other subtle fish. I have also cooked stuffed peppers, rabbit, chicken, seafood and even burgers on a cedar plank. I have also had excellent results with Oak planks, which work well with trout, and other slightly stronger fish, and chicken. Apart from Cedar and Oak you can also get planks in Alder, Cherry, Hickory & Maple.
I love plank cooking as I am kind of addicted to Cedar, unfortunately you cannot use Cedar for smoking as it becomes too overpowering and releases oils, which makes your food taste bitter, that's why i think plank cooking with Cedar is fantastic.
You can use planks in the oven, but personally i thought the flavours were not as good, as you did not have the smokey flavour to compliment the cedar or whatever flavour plank you are cooking with.
There are some good books on amazon on plank cooking here
The books are less than a quid, so well worth it.
Enjoy your plank cooking