Dont really have an "average". Down to 10kts in rough weather and up to 46kts if I want in good weather.
For me it's fuel consumption vs distance X what I want out of my day
The "norm" (if you want to call it that) ranges from 25 to 35kts when out cruising.
I have yet to do a "this year" time trial. I spent a load of time this year on a clean smooth bum (no, mines not like that!) and early results show 35kts at 3300rpm. With a 4800rpm top end, I may get the holy grail of 50kts - I'll let you know.
When I started boating I wanted speed, speed, speed. I tried convincing the family it was great fun as they crouched in the cockpit, enduring the occasional (and sometines not so occasional) slamming, as they got into denial mode.
After 15 years of this, I realised enjoying the passage, being able to cook on passage, for the family to watch movies whilst on passage, play games whilst on passage, be able to have a pee without slowing down, was far more fun than being beaten to death.
Ah, but what about the challenge of peeing standing up at 30 knots and not spilling a drop? Not perfected this myself yet, but with more practice I believe it can be done /forums/images/graemlins/laugh.gif