sx/sp - touch, and service (quality time is spent in helping someone else out)
sp/sx - gifts, and words (showing intimacy, but not too much)
sx/so - touch, and words (since time gets the two of you close, and words strengthen that social bond)
so/sx - time, and touch (since your sexual instinct desires to intensify the social relationship)
sp/so - gifts, and service (like nice things, but you really like giving and receiving nice things from loved ones)
so/sp - time, and words (the greatest gift is to know that someone loves you, and that you love someone)
Probably wrong, but what the hey?