Plain of Six Glaciers is one of the most spectacular trails around Lake Louise (that are relatively easily accessible, that is). It starts pretty much right at the Chateau:

Follow the path along the lake:

There will be lots of these guys around, try to resist and not feed them. It will be kinda difficult to do, they are very persistent.

The trail starts to climb soon after the far end of the Lake, going through some fairly densely forested areas. Do not worry about bears in the Summer, there will be lots of people around most likely as it is a very popular trail.

Keep going:

Looking back towards the Lake and Chateau Lake Louise, about half way or a bit more:

The forest will mostly disappear as you get higher:

Some spectacular rock slides along the way:

And even more spectacular cliffs. This is near the end of the trail:

Looking back towards Lake Louise from about the end of the trail.

Don't forget to stop by the Tea House on your way back for some tea and a cookie.

Walking back towards the Chateau:

Parks Canada will have some up to date info about the trail conditions here
http://www.pc.gc.ca/pn-np/ab/banff/visi ... a10f_e.asp. Beware if you go for a hike when the snow is still around, the trail crosses avalanche terrain.
Have fun!