I live in the Comox Valley, right about the middle of the Island on the east coast. I do a lot of driving in the region between Campbell River to the north, Nanaimo to the south, and Port Alberni to the east. In no particular order, these are my highlights:
The Old Island Highway 19A, starts about 20 minutes north of Nanaimo, in Parksville and ends in Campbell River. Slower than Highway 19, but way more scenic. And twisty! Frequent ocean views. Avoid 19 altogether. It's nice enough if you don't already live here, I guess, but there's no variety to the scenery.
Coombs Country Market in Coombs: I think of it as a smaller, landlocked version of Granville Island in Vancouver. Except that goats graze on the roof. A great place to kill a few hours at quirky shops and to check out the huge Asian-inspired statues and sexually-themed wood carvings.
http://www.oldcountrymarket.com/Cathedral Grove, en route to Port Alberni from Hwy 19. Beautiful old-growth forest just beyond Macmillan Lake. And the road to Port Alberni is especially twisty.
Qualicum Beach, especially if the weather is good. The beach itself is beautiful, and the town is spotless. Might have to do with the fact that there are no fast-food franchises allowed there.
Courtenay/Comox
Charming downtowns, hardly any "brand name" stores. Courtenay's Airpark and Riverway is a great walk that I take almost daily.
http://www.comoxvalleyguide.com/recreation/hiking/airpark/Island Musicfest July 9 - 11, considered one of the top ten in Canada according to a CBC online vote.
http://www.islandmusicfest.com/Comox Valley Classic Cruisers 24th annual car show, July 25. About 300 vintage automobiles from all over parked downtown last year.
Basic tourism stuff:
http://www.discovercomoxvalley.com/The village of Cumberland, just a few kilometres west of Courtenay. A lot of artists live there. The downtown is of course small, but real character. Seems like time stopped there a few decades ago, although developers are moving in.
Big Time Out music festival August 14 & 15.
http://thebigtimeout.com/That's all I can think of right now, GMF. Whatever you end up doing, you're doing your research, so I'm sure it'll be memorable!