I know it's heresy to suggest this here, but given how infrequently you fly, unless you run huge credit card tabs each month (personal or business), IMO your best bet would be to try to book 2 or 3 FF seats and use $$ for the others -- and have the $$ seats be for whoever in the family flies the most (so they keep building more miles). A Europe trip can easily generate 10k FF miles, which puts you on the road toward the next trip...and to status, but that's a whole other topic!