Maligne Lake is a finger-shaped lake. It is not very wide, but it is about 16 km long. The water is pretty still and very beautiful, along with the scenery. You need to take all day if you want to see the whole lake. The water stays cold year-round, so don't fall in. I wish I had known about the backcountry campground ahead of time.
This is one of the most beautiful places that I've ever been, along with the Grinnell Glacier trip in Glacier National Park, Montana.
There are several accommodations in and around Jasper. I camped at a park campground just outside Jasper proper. There is a hostel near the campground, outside of the town. There are several hotels and bed-and-breakfasts, etc., in town. I did not find out until I reached Maligne Lake, that you can reserve a spot at a backcountry campground on the other end of Maligne Lake. Apparently, you have to reserve a spot from a few weeks to several months in advance, depending on the time of year you want to go.
You can get a Western Canada Parks Pass or pay the daily rate at the gate.
You drive east from the town of Jasper, towards Edmonton, no more than 10 km and make a right turn. You take that road to the end, about 20-30 km. The Park Rangers will give you a map at any of the entrances to Jasper National Park.