My L322 is coming up to 114k now and I have no plans of getting rid of it anytime soon. What maintenance do people recommend at this mileage? I've already done the oil cooler a few months ago and I service it every 6 months myself.

Clean any rust off the underside, including the front and rear subframes, and spray with Lanoguard or even engine oil if you so wish.

If it's a diesel with dpf I would recommend getting the dpf cleaned, like, removed from the car and properly cleaned. 2012 4.4TDV8
2000 Honda S2000

At 100k miles there should be plenty of remaining soot capacity in the DPF to not need this at all. 2012 TDV8 Vogue (L322)

During those 100k miles there were, perfect scenario, 400 regenerations but most likely more.
So I beg to differ about the state of a dpf to have plenty of soot holding capacity at that point.
Based on my own experiences and based on the posts on here of owners having dpf full warnings.
It's also based on the fact the soot turns to ash and the ash stays in the dpf, that's how they work.
The dpf is a filter.
Part of preventative maintenance is, sure, in my opinion, to replace (very expensive in case of the dpf) or clean filters. 2012 4.4TDV8
2000 Honda S2000

I agree plenty of people are having DPF full warnings based on soot load due to poor driving habits and / or faults in the system i.e air leaks or failed sensors inhibiting regenerations and in these cases even if the DPF was new then they would still get the same DPF full warnings. The DPF has plenty of capacity to partialy fill with ash before it's soot capacity becomes problematic by which time the ECU will let you know. Filters only need changing when they are beyond their operational capacity and there is no case for changing them sooner as a preventative for future problems any more than changing your tyres 1/2 way through their original tread depth. 2012 TDV8 Vogue (L322)

We have the pressure differential sensor and the miles driven between re-generations.
Is there any other available data?
What are the values of a known new DPF compared to a used one or a DPF generating a DPF Full warning?
Do we know? 2012 4.4TDV8
2000 Honda S2000