Is there transportation between the two stations other than taxi?
Thanks.

Take a subway one stop north to 42nd Street/Times Square and change to the shuttle to Grand Central.

If by chance you're carrying much in the way of luggage it's far better to take a cab. The subway from Penn Station will leave you under Port Authority and the walk through the tunnels to transfer to the Times Square Grand central shuttle is long (seems like 1/4 to 1/3 mile if I'm guessing correctly). I've done it many times and although it's tolerable with just a small rolling suitcase it would be a real hassle with larger bags, especially at busy times of day. The cab ride should be inexpensive - about $6 with tip.

hate the connecting underground tunnels ditto Owen's remarks. Also certainly worth your while to go upstairs at Grand Central and look at the main lobby beautiful. One of my favorite buildings in NYC. Look at the facade out front (what is that entrance?) and see how it mirrors off a neighbor building.

Yes... if you do take the subway it's much better to walk upstairs at Port Authority and then walk the outside route to 45th and 7th where you can pick up the shuttle. The catch is that you pay subway fare twice because you leave and re-enter. Option is to take cross-town bus at 42nd and 8th and use the free bus transfer from your MetroCard Funpass (you did buy one when you arrive, right?). Personally, I'd walk rather than take a cross-towon bus on 42nd Street - walking is almost as fast and less aggravating. By all means do follow the suggestion to check out the renovated GCT. It's really amazing. Look up at the corners in the far end of the rooms and in one corner you''ll spot a black rectangle tha covers a small area of the stone on the wall and also the blue background of the vaulted ceilihng. It was masked off before the renovation and then uncovered and left in place afterwards to provide a contrat for before and after. It's mind-boggling to see it and then look at the contrast.

Thanks, people. We're healthy seniors but will be carrying well-filled carry on bags, so will probably opt for the taxi. Have seen the restoration at GCT but have only used it in connection with MTA Hudson Line. Traveling Amtrak up the east coast changes our usual itinerary.
Thanks again.

About the NY Airport Service ( http://www.nyairportservice.com/ ) uses smaller shuttle bus that picks up at Penn Sta (33rd St. corner of 7th Ave., Opposite Pennsylvania Hotel) and brings customers to their stop across from GCT, where LGA & JFK bound travelers purchase their ticket and transfer to larger buses.

A number of years ago, they allowed people to use this transfer for free, even if not going to the airport. I see nothing about it in their web pages, but you could call them (718) 875-8200 to see if that is still true.

Or, I suppose you could just board at Penn, and decide not to purchase tix at GCT and "walk away" (but tip the driver anyway!)