hi cheesewiz, i would suggest you take an airline with 8hours for the first flight then 8 hours for the next connecting flight so there would be a balance between flights instead of taking an airline with long hours at first flight then a short connecting flight to the Phils or vice versa. Another is u may check in earlier and take the seat after the business class just in case ur travelling with economy class, the legroom is okey on that seat and it would be really comfortable for him. Also, u should book urselves earlier, as we know December is peak season, airline tickets are high and mostly flights are fully booked.
Goodluck.