Tony wrote:
So here's the deal. You're at 11,000 feet doing say 120 knots over the
ground and your sea level destination is 100 nm ahead. It's late, ATC
is quiet, very little traffic, CAVU, you're pretty sure centger will
give you whatever you ask for.

What would you ask for?

I figure something like this: If I go downhill at 200 feet a minute at
my cruising speed it's going to take 5 minutes a thousand feet or 50
minutes to get to pattern altitude. "Hey Center, Mooney XYZ requesting
lower -- can you give me cruise at 5000?"

If they say yes I'll back off the throttle, the airplane is already
trimmed for the right speed, and start down. Close to 5000 feet I'll
ask for lower and continue down, maintaining my en route cruise. I'd
for sure be managing airpseed, CHT, mixture, and so forth -- I look at
those things every time the altimeter unwinds another 500 feet.

What would you do?

I believe you will also have to tell them your going to descend at 200
FPM as they expect a higher rate. I'm betting they will allow it but
best to let them know. I know you have to tell them if you can't climb
at 500 FPM and I think they expect the same on descent.