I had a great time in Banff and can't wait to go back. We did two days of downhill at Sunshine, two at Lake Louise, and two days of XC.
On the first day, we went to Lake Louise and did the Fairview Loop (7.5km round-trip) listed on the Parks Canada Lake Louise WInter Trails brochure. It was snowing a little bit, with temperatures hovering right around 0 degrees C; not bad to have a groomed trail, though we didn't get any views while skiing.
On the second day, we skied up to Boom Lake (listed in Chic Scott's book; somebody did a nice description of it here). The trailhead is only 6km off the Transcanada Highway, about 1/2 hour from Banff, but we were amazed at the solitude -- we didn't see a single person out, on a Thursday in pretty nice conditions. It's a really nice trail -- enough up and down to be mildly interesting, but flat enough to be doable in most conditions, even by beginners. 5km each way. The lake itself is pretty, but when we got there the wind was pretty intense (it actually knocked me over, at one point), so we got back in the trees pretty quickly.
Anyway, good times!