I've hiked in the forbidden plateau area... started at the base of mt. washington and hiked to the top of mt. albert edward. to do it comfortably I say take three days, one to the base of the mountain, a day casually hiking up and around the alpine and back to the camp, and a day hiking back out to your car. the view from the top of albert edward is pretty sweet. you could do it in two days if you want, but why rush it? with that in mind, there are many options around that in the area... you could start at the old forbidden plateau ski hill and hike in from there, it makes for more elevation gain and a longer hike in, but with the access from mt. washington, why add more hiking that is in the forest when you can get to the alpine quicker by the previously mentioned way? Also, if you are more comfortable with mountain travel you can traverse the ridge going south from albert edward towards comox glacier, i haven't done this yet, but i've heard great things about it... another option would be to continue west from albert edward and hike down to buttle lake. both the traverse and hike down to buttle like will probably require you to do some more searching of information as for trail locations and what not.
deeper in the park there is a hike i've been trying to do for a while now, but i keep getting shut down for weather. the elk river hike. gets you in to the area with with highest peaks in the park. if you go hike the elk river and it's a clear sunny day, it promises to be awesome.
I got back about an hour ago from Cape Scott - now that place is awesome... if you're ever up island or have the opportunity, i would highly advise you to check the place out.
well, i think i've said enough for now, hope i was of some help.