Call me inexperienced, but I have never had to make a connecting flight through New York. One flight option has us flying into LaGuardia with our connecting flight for Europe departing from Newark nearly 4 hours later. How difficult or how much of a hassle is it to get from LaGuardia to Newark? Thank you.

LaGuardia airport's website lists all the options available to you to transfer to Newark. Aside from a cab or private car service, you will have to take a bus into the city and then transfer on to another bus that will take you to the airport. Four hours isn't really alot of time especially if you are transfering during a rush hour. Since you are going on an international flight which requires a very early check-in I would consider a car service, which under the best circumstances could have you there in about 1 hour, give or take a few minutes.

Most estimates for travel range from 60 to 90 minutes. You might be cutting things a bit close. Should your LGA flight be delayed you will have problems
Trans options;
Airport bus to city, airport bus to EWR will cost around $22 a person. A minimum of 90 minutes possibly more
Airport bus to city, train to EWR. Around $23 a person. at least 90 minutes.
Limo - about $65 plus around $11 in tolls and tip is extra. A Yellow cab would be about the same. With luck the trip could be done in under an hour assuming no traffic delays (an assumption I wouldn't make). Time of day of trip would be a major factor.

Thank you--it seems that while it is possible, I don't think I want to do it!

For international flights out of the NYC area, it is always best to have your first leg fly into the international airport of your choice (JFK or Newark) before leaving the country. There are simply too many variables between the weather, traffic, and airport crowding in the area that can delay your ability to transfer between LGA and the other airports.

The other option is to arrange your flights so that you get into LGA late in the evening, and stay over and get your flight from Newark the next day. That way, you have a built in buffer... We've done that before for international flights...