We did a 6-day, 5-night, backpacking trip in Assiniboine Provincial Park in the first week of September, 2016. Here is my brief trip report and hope it helps when you plan your trip.
The temperature was between 33F to 55F. It rained a lot during the trip. If you do backpacking like this you should ensure yourself can comfortably pitch tent in a rain. Even better, double check the weather forecast and avoid the rainy weather if you can, as a good sunshine indeed can make the trip a lot enjoyable.
We started from Sunshine Meadows. The Standish Point was a must do. If possible, I think it deserves a sunrise or sunset as the view is incredible there. It was cold and windy on top of it.
Campground at Howard Douglas Lake in Banff National Park needs reservation. There is a small pass on the trail. With 15 minutes hike, you can see very nice view in this area. It was good for sunset at the time I was there but I think it should be good for sunrise also.
Porcupine Campground is in the valley. If you decide to camp there, be prepared for a steep downhill and up to the main trail.
The water in Og Lake had a lot of small bugs when we camped there. The view and facilities in Og Lake are not nearly as good as Magog Lake. Since they are pretty close in about two hours hike, if I did the trip again, I would avoid camping at Og Lake.
Magog Lake campground has a covered shelter. Try to find a spot close to the shelter.
Along the trail, all campsites have metal bear box, except for Howard Douglas Lake, where you need to hang the food on provided racks. If you camp there, you will need to bring a sack to hold food.
Spots close to Nublet provided the best view, where is good for both sunrise and sunset. I took both 17-40 and 70-200 lenses and felt they were both useful up there. For your reference, while the sunrise was at 7am, we got up at 4:30am to start the hike to Nublet.
My GPS track, Sunshine Meadows To Assiniboine.gpx, can be downloaded from GPS Tracks Collection.
Sunrise at Nublet. Facing Sunburst Peak, Mount Assiniboine, Sunburst Lake and Magog Lake.
Sunrise at Nublet Facing West
Standish Viewpoint at Sunshine Meadows
Sunset at Howard Douglas Lake. The view is incredible with a little hike to the pass above the lake.
Sunburst Lake with reflection of Mount Assiniboine.
The hike to Nublet