Like most others, we try to sleep for 3 - 4 hours when we get back, then keep going until late evening. Back into normal routine the following day and another early night usually sees us back on track from then on.
The last couple of long-haul trips we've taken (one to Florida and one to Canada), we've booked a day room at an airport hotel and slept there before driving home. Although it seems like an expensive few hours (around £50), it's been well worth it for us to make the long drive home so much easier - and hopefully much less dangerous - as we're not still half asleep from the flight.