2 Senators, at least one representative, and the ability to spend all of their massive tax base purely on NYC (although there would be more people working in NYC-State than living there).
If we are going to start adding states again, then let's get them all divided up properly. Texas splits to 5 states (as was left on the table when it joined the US), maybe some of those territories will join in, Washington D.C. could give it a go (although it makes as much sense to me as "living" at City Hall in any city).
"Texas splits to 5 states (as was left on the table when it joined the US)"