Well, the easiest thing to do is work backwards to determine if the cost-per-mile is acceptible to you.
Accruing 12,000 service points should cost about $1000. It can be done more cheaply, but $1000 is a nice round number and is realistic for two Europe-west coast US flights with connections.
140,000 points / $1000 = $0.007 per point -- which represents excellent value when most people value mileage at around $0.02 per mile. If you don't have lounge access currently, the lounge access is a nice benefit, too.
Hope this helps you make your decision.