Passenger (and luggage) weight makes a huge difference for fuel burn and overall weight. That said, planes that are above maximum landing weight are generally bound for a very distant destination - on an SEA - LAX leg the plane is almost certainly nowhere near full on fuel, it under the maximum landing weight from the start, and can land immediately without a problem.
If it is going for somewhere far away, however, that gives the crew plenty of time to burn extra fuel on the way by operating inefficiently (turning on the APU, flying at inefficient altitudes or airspeeds, etc), and in any case if enough passengers are missing that the fuel burn will change significantly that'd probably push it back down under the landing weight limit.
The whole circling to burn fuel or fuel dumping thing usually happens when the plane has to make an emergency or unexpected landing; here the typical scenario is that the plane is fully loaded with passengers and luggage, and has nearly-full fuel tanks for a long cross-country or international route. Shortly after takeoff, a technical issue is identified, and the plane needs to shed weight before landing to avoid damaging the landing gear and requiring a costly inspection before returning to service.
The other scenario where circling to burn fuel can happen is if there's a wet runway or other such issue that reduces braking performance. Again, though, this is mostly an issue if you have a fully loaded plane ready for a very long route.
If it is going for somewhere far away, however, that gives the crew plenty of time to burn extra fuel on the way by operating inefficiently (turning on the APU, flying at inefficient altitudes or airspeeds, etc), and in any case if enough passengers are missing that the fuel burn will change significantly that'd probably push it back down under the landing weight limit.
The whole circling to burn fuel or fuel dumping thing usually happens when the plane has to make an emergency or unexpected landing; here the typical scenario is that the plane is fully loaded with passengers and luggage, and has nearly-full fuel tanks for a long cross-country or international route. Shortly after takeoff, a technical issue is identified, and the plane needs to shed weight before landing to avoid damaging the landing gear and requiring a costly inspection before returning to service.
The other scenario where circling to burn fuel can happen is if there's a wet runway or other such issue that reduces braking performance. Again, though, this is mostly an issue if you have a fully loaded plane ready for a very long route.