What maintenance do I need beyond 120,000?

You can just extend the scheduled services using the intervals suggested for the previous 120k miles. One exception is that the cooling systems need to be drained and refilled every 50k miles after the first time at 100k miles. The other item which is not in the "official" schedule is a periodic drain and refill of the transmission fluid (I suggest every 60k miles and if you are conservative a first one at 30k miles). I also change out the PCV valve when I do the spark plugs (every 100k) and consider replacing the engine water pump and serpentine belt at 150k miles when you do the coolant.

JeffD

 

If the document you are referring to is What services you need and what you don't | PriusChat then you are at the right place.

Sad but true that most dealerships pad their profits with "extras" that are not needed. Like you are doing now, one must be educated to what you really need if you are not mechanically inclined. Galaxy has done this for us with his document above.

My kids are always calling me with the same questions that you have, what do I really need and what not?

 

I couldn't help but comment since their is so very little mention of the timing chain on a Prius.
My Gen I prius didn't get one until 250K and my current Gen II 2006 Prius received one at 298K - keep in mind most of the time it is not the timing chain itself that fails on a Prius but the timing chain guides.
So, Betsy happy rolling! It sounds like you just got yours broken in.

~currently looking down the nose of 400K (@398K on the odometer) with the cruise control set on 75 mph headed into the 15-20 (mph) Kansas wind with gusts 30-40 and showing 44 MPG.

 

I don't know if it's in the manual, but if you are going to keep a car a long time hinges, latches and other metallic moving body parts should occasionally be lubricated.

 

"I came across a document someone on this forum posted giving an extended maintenance schedule for 2004-2009 models going up to 300K"

I'd love to see this document.