A few things to keep in mind with your UA Gold status

1. Regardless of the fare class of your ticket you can reserve an Economy Plus seat in advance and will not be charged for it. Non elites are frequently charged over $100 each way on a trans Atlantic fight for the privilege. This privilege is only available to UA Golds and above. If you fly UA as a Lufthansa elite you would not get the extra leg room.

2. Star Gold Lounges: As long as you are on an int'l itinerary you can use the airport lounges. Just show your Star Gold boarding pass. You would be awarded this privilege regardless of which *A carrier you fly or credit your miles to.

EWR-GVA is 7,740 miles r/t, plus as a gold you get a 50% bonus would yield you with 11,610 redeemable miles r/t. So after two r/t you would have enough miles to upgrade one way plus the co-pay based on the fare you book.