Here are some excellent resources for finding big trees:
Port Renfrew Ancient Forest hiking guide: Be sure to check out the local forest conservation group, Ancient Forest Alliance, hiking guide to the extraordinary trees near Port Renfrew, BC.
http://bigtrees.forestry.ubc.ca/ BC Big tree registry lists the largest, tallest and widest known trees for most native BC tree species, with some info on there location. Follow instructions on the website to submit your own record-sized tree.
http://vancouverislandbigtrees.blogspot.ca/ An interesting resource for finding big trees as well as information and perspective on a variety of subjects pertaining to old-growth forests.
clubtread.com A meeting place for the Vancouver hiking community. This is a great place to meet other hikers or to submit questions on a forum a local hiking expert can likely answer.
Trails Venture BC has recently published an up to date map of the North Shore hiking trails. I have not seen it yet, but the authors explain that they have mapped significant trees across the area.
Outdoor Vancouver is a free online hiking guide. They have added excellent directions to visit the infamous large remaining cedar tree in Lynn Valley.
Back Road Mapbooks ($25-30) are essential for travelling along BC’s backroads and they conveniently label many notable trees. Find this at MEC or most highway gas stations.
The only official local big tree hiking guides were published by Randy Stoltmann and the Western Canada Wilderness Committee in the late 1980s and 1990. These are out of print but can sometimes be found, if your lucky, at used book stores or online book distributors such as Amazon.
Vancouver Big Tree Hiking Guide 
Hello, we publish topographic trail maps for SW BC and, due to our interest in old-growth, we show the locations of old-growth trees, groves and forests on our Southern Chilcotin (upcoming 3rd ed), Stein Valley, Chilliwack East, Chilliwack West and North Shore trail maps. These particular maps are one of the best resources for anyone trying to locate old-growth in these areas (and are much more accurate and detailed maps than Back Road Mapbooks that you mention on your site). Let me know if you would like more info re our maps – they range in price from $9.95-16.95. Our website (trailventuresbc.com) also includes info and pics of the forests of these areas.
Perhaps you could mention our maps/website in your ‘Other Resources’ page? We will link to your site regardless.
BTW, love your site. Would love to see your site expand to cover Cypress, Seymour, etc areas although we know how much work this involves! We will be adding some info to our site re North Shore trees in future (the North Shore portion of our website is a WIP).
Tim
Trail Ventures BC
http://www.trailventuresbc.com
Thanks for passing me the link, Tim. I’ll be pleased to add it –sounds like a great resource. Pretty soon (once my thesis is done) I plan to update existing sections and add a few more sections. You are right, it does take a lot of work!