Given that United's Polaris, Air Canada's Signature Suite and Singapore's Krisflyer lounges only allow access for Business Class passengers, and assuming:

• Passenger flies irregularly, but exclusively in Business for international sectors and First/Business domestically,
• Passenger has purchased United Club or Maple Leaf Lounge for lounge access when travelling North American itineraries,
• Passenger doesn't play the credit card points game and has no inclination to make flight redemptions
• Passenger doesn't intend to fly Lufthansa and so doesn't have to make the choice between Business Class or Senator lounges.

What is the real benefit of achieving Star Alliance Gold?

P.S. I'm writing this post in the Air Canada and Singapore Airline forums as well, to get a wider response.