I personally wouldn't use Impersonation. I'd say this is imitating as one specific Person. Specialization in the book says "By Metatype (Ork, Dwarf, Human, etc.)" so it doesn't look like you would get into party UNLESS you impersonate a person that is on the guest list.
I would first use Etiquette, if it is about "blending in" as a person of a specific culture (i.e. high society). You know how these people talk, react, walk ... so from the get go one could presume you are not a nasty Shadowrunner.
If there is any doubt about your role, I'd let you talk your way out using Con. Or use Con from the very start. It seems a very versatile skill, as it is built to fool people. Go out, call yourself Mr. Rodriguez, and sell some useless junk for a completely over the top price to gullible people. Thats what people pick this skill for, isn't it?
Anyway, thats how I see it.