"GS Reception" as a totally discrete check-in area is found in SFO, LAX, IAH, ORD, DEN and EWR that that should feed you into the front of the security line. EWR involves identifying yourself as GS when you get to security. IAD has one end of the check in counter roped off exclusively for GS check-in and is always staffed but no special arrangement for security.

Some other airports may have a check-in counter with the GS logo but it is not typically spelled out. In my experience when I approach it someone will say "GS?" and when I confirm they say "will be right with you". And some stations only have premier and regular check-in counters. No special arrangements for security.

NRT GS check-in used to be with in Zone Z with ANA First Class (nice because with a dedicated security area like SQ First Class in SIN) but last time I went through they told me UA had relocated all check-in to the regular counters. LHR is just a specially marked check-in counter. There is a separate GS mini lounge within the LHR United Club, however.

The GS check-in experience really does vary airport by airport from the regular premier check-in to a nice, personalized experience.