I'm based at Las Vegas with America West, and it is busy enough at LAS
that I rarely use managed speed until the last couple thousand feet on approach. We almost always get a speed restriction from ATC such as "Maintain 170 knots until 7 DME
" or something similiar. I'll get the plane configured comfortably for 170, then at the appropriate point push for managed speed and finish configuring for landing.
On takeoff it starts out in managed, and goes to selected if we need a speed other than what the FMGS is programmed for; for instance if we are vectored off of the departure route and need a quick climb to get over some mountains we'll maintain a lower speed to increase our rate of climb. Or if the plane ahead of us is slow to accelerate we've had ATC tell us to slow down for a while too.
As for the autopilot, it is up to the person flying, and the company policies. Normally it will be clicked off when on final with the runway in sight. However in places like LAS
where we often get 'slam dunk' approaches we'll manually fly it when we can tell that the plane isn't able to do what we want on its own. The airbus is set up so the autopilot normally flys very gently - sometimes ATC instructions require us to be a little more abrupt than that.
One smooth landing is skill. Two in a row is luck. Three in a row and someone is lying.