Aruch HaShulchan: Do You Sit At The Head When Your Father Comes To Visit?
TheShulchan Aruch paskens (YD 240:2) that you may not sit in your father's place at the table. The Aruch HaShulchan writes (11) that this only applies in his house, however if he comes to eat in your house, you maysit at the head and your father beside you.
The She'arim HaMetzuyanim B'Halacha writes (143:2) that the Aruch HaShulchan is only coming to explain the Minhag why sons sit at the head of their own table, but the general minhag is not like that, and one should let his father sit at the head.
Either way, the Aruch HaShulchan says that your father washes his hands first and gets served his portion first.
Important Note: We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be thefinal word on this topic. One should consult a Rav before drawing any conclusions.