By definition, loyalty programs are for frequent travellers.

If you are looking for upgrades, the Ambassador program may be the best choice, as it is a paid access program, independently of how often you stay at ICs, with guaranteed upgrades and benefits.
http://www.ichotelsgroup.com/interco.../gb/ambassador

If you are looking for free nights, the Point Breaks offer is a very good opportunity (but limited selection of destinations and dates). You can even use your Amex rewards miles.
http://www.priorityclub.com/hotels/u...m/pointbreaks/