We were on a summer long trip and really into doing mountains in a push. It was decided that the DC route with its well trodded path would be the most likely route to go this way.
The slogging began at 7:00 pm on July 23rd. The Muir snow field was reached quickly and we realized that our hopeful 11:30pm arrival at high camp would be easily obtained. We hung out for an hour or so just below camp Muir and the continued at 10:45pm. Just as the guided parties were leaving we made a sneaky pass and got in front. Once around the initial bowl we looked back and saw the massive quantity of people heading up - It looked like christmas lights- ridiculous. We cruised past the higher Ingram camp passing many parties and then more or less followed the trail - yes it was definitely a trail - all the way to the summit. We summitted at 5:30 am just as the sun was rising. Pretty wild. The descent back to the car was cruiser and we arrived at 11:45 am. Just under 17 hours round trip.
Tips for climbing Rainier: Leave early. midnight departure from Camp Muir should be considered mandatory. conditions could get dangerous if you descend too late.
Crowds are a huge issue. If doing it in a push you must get ahead of the guided groups right off the bat at Camp Muir. It could be difficult to pass later on.
Have fun and don't fall in any crevasses.