Well, Skyline's in Jasper (on the high part of the trail you look down on the Jasper townsite), and is quite a drive (4 hours ish) from Banff townsite. If you do end up that far north, it is very very nice - I do it a lot.

here's one with good weather:
http://bofh.ucs.ualberta.ca/beck/pictures/skyline2007/
and not so good weather:
http://bofh.ucs.ualberta.ca/beck/pictures/skyline2008/

Skyline tends to be "popular" when you book it. (i.e. it may be hard to get the actual campsites you want) but if there is any sort of weather there will be nobody there at all because people show up unprepared and wimpy.

I've had hikes where parks canada told me the sites were all full, and I went and ran into three bailing irishmen with rented gear on their way out on the first day, and one local like me the rest of the time. the rest of the trail was deserted. (I actually pray for crappy weather the first day of a skyline hike because it chases everyone else off it