Go directly to your hotel, and drop off the bags. We found that getting out in the fresh air and "exploring" works best for us. Expecially when the room/lodging is not available. If it is available we hit up the shower, and then go out. This can be a great day to do the hop-on, hop-off bus tour, or the historical walking tour, or maybe even a biking tour. If we do anything more than a 15-20 minute "cat-nap' we found that our "clock" will not re-set; snd we end up with a bad case of jet lag. In a couple of weeks we will arrive in London at 8 AM. This will be after 17+ hrs of flights and limited sleep. We'll head to our B&B, drop off the bags, shower, and then take in some of the major sites. We make sure that we stay up until at least 9 PM. We sleep "like a log" and awake the next day ready for a lot more.