Thanks everyone for the pointers. Seems to be a US/Europe split here (can't speak for the rest of the world). Getting DPs free is easy in the US because the relevant loyalty plans cover spouses in the US... here in Europe it appears that even legally married heterosexuals need to pay for additional drivers regardless of loyalty scheme... so I'll keep shelling out in France but look forward to getting my DP as a freebie in Nevada (er, so to speak.)