We will be in New York for three days and plan to use subway and bus. We would like to buy the metrocard. Is there a one-day unlimted pass? If not, how much is a typical fare for bus and subway ride. Can my wife and I share a card? Since we are both over 65, is there a senior discount? Is there a place at Laguardia that we can buy the card so we will have it after we arrive by cab in Manhatten?

There is no longer an unlimited one-day pass. You'll pay $2.25 per ride, and two people can share a regular, unlimited Metrocard. If you take the bus (and look like you are 65), you can pay in cash (coins only) the half-price senior fare. You can't really do this for the subway because you must buy a special senior reduced-rate Metrocard, and it's just not practical to do that for such a short trip.

Load the amount of money you want onto the card and then swipe twice every time you enter the subway. You get a little bonus if you put on $10 or more.

If you really, desperately want to have your Metrocard in hand when you hit the streets in Manhattan, there is one place at Laguardia where you can buy them. It's a machine in the dead middle of the main terminal (Terminal B -- where American Airlines is), and it's on the baggage-claim level. It's in an unmarked hallway in the dead center of the airport and is hard to miss if you are down there, but you can't pay cash.

Thanks for the information. We don't think we look like 65 but we are and do have ID cards (even the senior fare cards for the Chicago RTA) if we need to prove it. We may just use the cards on the bus as we don't usually have that many coins. I assume we can use our credit cards in the machines to get the Metrocard.

Yes, you can use a credit card to purchase MetroCards from the machines.

When you share the MetroCard, as Doug said you will swipe it twice to pay for the two of you. For the subway, you will swipe at the turnstile, watch for the display of "GO" and move through the turnstile, then hand the card to your spouse and repeat. (If the display reads "Swipe again at this turnstile" which occurs if you swipe too slow or too fast, don't be tempted to switch to a different turnstile—keep trying at the same one or you may be charged an additional fare.)

On the bus, one person can just dip the card twice into the farebox.

If you transfer from one bus to another, the card should track the two transfers and require only one dip to continue your journey. Watch the display to see if it reads "2 XFR OK" or the like.

Are you saying there is no additional charge if you transfer from one bus to another? What if you transfer from a bus to the subway?

Yes, generally one free transfer within 2 hours, with some exceptions http://www.mta.info/metrocard/termsreg.htm

I hit send too soon.. Note that if you pay by cash on a bus, you can only get a paper transfer to another bus. With a Metrocard, it works bus to bus, bus to subway, subway to bus

The free transfers with the Metrocard can really come in handy. I often go down to Union Square to shop for groceries. If I go down on the subway, I can come back on the bus for free as long as it's within 2 hours.

Technically you're not supposed to be able to use the free transfer to create a "round trip" journey, but as Doug said, combining bus with subway is a way to do it.

(This is why you can't transfer subway to subway--ride one subway, go outside the station/turnstiles, return within two hours, and ride again--this will NOT work.)

Actually, it will work, depending on the line. You can transfer between the 4/5/6 at 59th to the F train at 63rd (as long as you have a Metrocard), and I believe you can do the same with a couple of lines in Greenpoint, Brooklyn for the Franklin Avenue shuttle (don't quote me on that, however).

The pay as you go metrocard can be shared by up to 4 people but the 7 day UNLIMITED card for unlimited rides over a period of 7 days from first use ($29) is not shareable. http://www.mta.info/metrocard/compare.htm
While there is a reduced rate card for seniors, it requires getting a photo ID and for a 3 days visit, seems like a waste of time. For longer stays, yes, makes sense.