I just had the 16k mile service. Oil and filter, final drive oil change, Coolant change, Brake fluid change, valve check (3 valves out of adjustment!), rear pads and.... another air filter. The first air filter was changed at 8k miles and having requested to see both upon removal, I was happy they were changed. 16k intervals for the air filter seems too long!.
As regards cost, and I'm not trying to get a dig at those who are on the Honda 4 service plan @£550 stg,
My first service was free, 2nd service was £180stg which included an air filter @ £51.63 not scheduled, and now this service @£400 stg. Ignoring the air filter for the second service, that's around £528 for the 1st 3 and the 24k service is just oil and filter so another £130 approx. That's £658 for 24k miles. Happy with that.
I assume with the Honda service plan, the schedule is rigidly stuck with, so if an air filter is needed along the way ( before its time for change) it will be an extra charge!
Just for the record
Honda air filter part number 17210MGH 640
Honda rear brake pad part number 06435MGED01