We've never been in the serviced sites at Whistler so can't comment on those. I do know the serviced sites at Wapati are just a parking lot.
Whistlers has nice showers and the show they put on at the ampitheatre was actualy pretty good. I think the firewood permit is awesome, we like to have a fire going so $8 is pretty reasonable imo. Of course there's lots to do since you're so close to Jasper.
Do you just want info on the campground or would you like suggestions on other activities in the area? I know both areas quite well if you want some ideas.
