I was 'mightily' impressed by IHG last year with their Big Win promotion.
I earned 134,461 points with about $97 spend per night (out of a total of 7 nights).
After my initial hesitation, I'm also participating in the current promotion 'Into the Nights' since it provides 2 free nights (or 80,000 points) with just 3 Holiday Inn stays (most premium IHG hotels can be had for 40,000 points/night).
There are some OK offers around this time that give you 50,500 points (who made up this number?!) with 3 stays.
I wasn't targeted for that, so would have to do a lot more for 50,000 points. 8 stays for a 'meagre' 14,400 points – I think I'll pass on that offer.