My first thought on reading your post is to strongly encourage you to book your accommodations (if you are not camping) as soon as possible because the August long weekend (2nd through 5th) is the busiest time of the year. Here in Jasper National Park, that weekend is always a sell-out of very close to it for all types of accommodation, and the accommodations in neighbouring towns or areas (min. 1+ hour drive) are also very, very busy.
I love glaciers! For more first-hand evidence of how glaciers "work", be sure to visit Mt. Edith Cavell. The day-use area was covered in glacial ice less than a hundred years ago and you can see what remains of the Angel Glacier and get an idea of how fast it is receding, and what a landscape looks like after recent glaciation and when vegetation is starting to re-colonize the area. Last August, 70% of another glacier on the mountain "gave up the ghost" in a massive ice fall that caused a tsunami-like wave and flooding. (That one is called the Ghost Glacier.)
Actually, evidence of the glaciers is visible all around you in the Canadian Rockies... here are just a few examples.
When you are in one of the major valleys (the Bow in BNP, or the Athasbasca River valley in JNP), look for the "hanging valleys" on either side, whose floors sit perpendicularly above the main valley. Lake Louise, Moraine Lake are both in hanging valleys. Lake Agnes above Lake Louise is a hanging valley over a hanging valley! The Maligne valley is also a hanging valley. Do a bit of googling ahead of time to learn the mechanics of how this occurred.
Another visible sign of the glaciation here in Jasper townsite ... when you look around at the surrounding peaks, the smaller ones (Signal, the Whistlers) are rounded - scoured smooth when the 1000m thick glaciers filled the valleys and covered them. Higher peaks like Mt. Tekarra and Indian Ridge (both adjacent to the two mountains I named earlier) are rocky and jagged - they would once have been nunataks, islands of rock jutting up through the ice. They weren't covered and therefore weren't scoured smooth.
At the Columbia Icefields visitor centre, you can see lateral moraines on either side of the Athabasca Glacier, and surrounding the visitor centre, there are terminal moraines, as well as bedrock that shows scratch marks where glaciers moved boulders over the surface of the rock.
Edited: 5:24 pm, June 30, 2013