Switching to S-Class – Watch out for what?

Hello, I would like to switch from my Phaeton (with which I am basically quite satisfied) to an S-Class. Optimal would of course be a well-equipped model that is a little older (leasing vehicles don’t really come into consideration because of my annual mileage). I looked around a bit on the usual used car platforms and found a few models that I find interesting and which fit into my budget. But as that is so, it could be I hope that one or the other can warn me of pitfalls that would escape me (I’m really more of a driver than a hobbyist) or what you should pay special attention to. What the maintenance costs look like in reality and what it looks like with inspections etc. For example, there is an S 320 CDI long version, EZ 10/2009, 200,000 km S 320 CDI DPF, EZ 03/2008, 89,000 km and a S 420 CDI with AMG sports package S65, EZ 05/2008, 159.0 00 km In general, I would like to know how to set the costs and how many kilometers I can still ride realistically with the cars (I drive about 50,000 – 60,000 km per year, so it should be convenient). I know, it is unfortunately still kept very general, but maybe someone has one or the other tip for the change. Therefore, thank you already in advance for your trouble!