bassionet (sp?) possitions are usually marked on seating charts, steer clear of those. It seems kids are kept out of exit rows (maybe because of the frequent flyer who always ask for them
) so if you sit near them your odds of being kids/infant free are increased.
if you want a kick free back go for a back row in a section, provided you don't mind missing on on some recline in the seats. Only, don't do it near toilets...
hope that helps