Originally Posted by
Cloudship
Yes, it is called the Airporter. Surprised so few people know or use it. Not as fast as a taxi, but easier than the subway and much cheaper ($15 each way from LGA, $17 each way from JFK).
Grand Central is pretty inconvenient to the Millenium Hilton. I don't think taking a taxi from LGA to the Millenium Hilton would be much more costly than the shuttle to GCP and a cab or uber from there.
If you feel the need to take a shuttle find one that will drop you off on the west side, preferably Penn Station.