In the past I have found that moving points into a Hilton account to be the most effective. I used them for a Hilton in Helsinki about 3 years ago and got about €350-€400 of accommodation for free. It worked out at about a 2-3% return on my spending - which if I remember correctly was about twice or more the return I was getting elsewhere. However I would recommend signing up for the Hilton scheme first and then checking out the hotels you would like to stay in before converting your points. That way you can get an idea of how to compare across the various deals on offer