We plan our flights (corporate heli) to stay mainly outside anything other than Class G and request a Radar Information service from appropriate en route ATC units. We do ask to cross Class D on a fairly routine basis but always have an alternative plan to go around or under.
It is simpler and it gives you more flexibility (ATC can't / won't control you. They don't really want you in their hair in Class A due to workload, especially in the south of the UK). The only exception is obviously where we have to make an instrument approach into an airfield surrounded by Class A, although we normally go in under a SVFR service.
That's just the way it seems to be.
