The post two above yours (by Tr60) gives a good example.

Personally, I don't bother with credit card churning. I've earned about 300-400K miles per year for the last few years just through butt-in-seat flying (total of $3-5K per year spent on fares) and credit card spend ($30-40Kish, but a lot of that is spend in categories that qualify for double points on my card). I don't do hotel points, except I did take advantage of the IHG Win Big promo at the end of last year to earn about 100K IHG Reward points for staying four nights in IHG properties.

If/when it becomes harder to earn enough miles the traditional way due to airline program changes coming down the pike, I may look at credit card churning and using those miles to fly most of my trips rather than pay cash for my tickets, but for now, I'm happy with where I'm at.