I've never done an actual mileage run, but I've done plenty of unnecessary flying to get status. Last year was the most I've ever flown -- over 100K BIS miles, including 8 trips to Europe, all on my own dime and mostly on DL, but I did accidentally end up with 2P status on UA. Curse those tricked fares!
If another opportunity like the DL MAD fares comes up, I'll jump in, but presently I only expect to make GM if I stay with DL, and I don't expect I'll begin doing real mileage runs. I like to look around when I get there.