LaGuardia Airport (LGA), so close to Manhattan, yet such a pain. It has no direct rail link so every option is subject to road traffic delays.
LGA’s website has extensive transport listings but all present best-case scenarios. Here are the options, with strengths and weaknesses:
Taxis: fares are metered (not flat-rate to Manhattan like JFK) plus tolls and tip (see sample fares). Be prepared for long lines in peak times. Destinations in Manhattan can be around $30, so for two or more passengers taxis are a better options than the shuttle services or express buses.
Car services: About.com has a good summary of pros and cons of car services, plus listings of the major companies. For trips to LGA, car services are straightforward and often competitive with taxis. For airport pickups, though, it is crucial to understand all the potential charges and penalties, and decide on indoor pickup or curbside (call on arrival) pickup. To avoid a financial hit for the standard LGA flight delays, call on arrival services are financially safer though can result in some waiting time.
Shuttle services: due to traffic, these shared services are more miss than hit. Every passenger’s stop can cause huge delays so pick-up times for trips to the airport are ridiculously early, and trips from the airport can be interminable but they do go door-to-door. For parties of two or more, a taxi is often price competitive. LGA’s website has comprehensive listings.
‘Express buses’: these buses go to/from the major stations in Manhattan (Grand Central, Penn Station, Port Authority). No detours, but like shuttle services, parties of two or more can often do better in taxis. Not the best for those with luggage or those new to New York as then a taxi or public transportation are needed to final destinations. NY Airport Service and NYC Airporter are the main options. (note: both the shuttle services and ‘express buses’ offer airport to airport services, see here for options by airport.)
Public buses: now for the real fun. The Rapid Traveler has riden the M60 since he was a boy, until recently marveling at seemingly the only airport buses in the world to not have luggage racks, but alas, most of the fleet has been kitted out with racks in the past several years.
There are five buses that serve LGA, four of which have the Q for Queens prefix (Q48, Q33/Q47, and Q72), all the Qs eventually connecting to subway lines, but not useful for the majority of visitors except for Mets games and the US Open. The lone M for Manhattan bus, the M60, is rarely sighted, except when traveling in packs. Typically multiples of each empty Q will zip by before a packed M60 saunters up.
NYC buses are unfamiliar with the cash economy. They accept MetroCards, of which not all LGA terminals have vending machines, or coins. $2.25 in coins = countless delays by unprepared travelers.
The buses make only one pass through the airport, unloading and loading passengers at each terminal. This creates even more delays as passengers at the first terminals load in, making it difficult for later passengers to escape. The bus starts at Terminal D (Delta) and then ascends C (US Airways), B (Central Terminal), A/Marine Terminal/Delta Shuttle. In peak times it can take 30 minutes or more to go from Delta to the airport exit.
Once out of the airport, the ride west through Queens typically is efficient except for staff shift change times when airport employees make use of nearly every stop.
Except for those heading to Upper West Side, Harlem or the Bronx, the best subway connection is the N/Q at Astoria Blvd (see subway map), the last stop in Queens. Famished travelers can stop at the famous Neptune Diner. The N/Q provides subway access to Midtown and beyond in about 15 minutes. If continuing on the M60, once in Manhattan there is a grinding slog along 125 St in Harlem, crossing the various subway lines all the way to the 1/2/3 on the Upper West Side. Every stop is high traffic, starting with the grocery carts from PathMark at Lexington Ave. The Manhattan section can easily take 30 minutes or more.
Traveling from Manhattan to LGA, the N/Q is the only option that can fully bypass Manhattan gridlock. Once out at Astoria Blvd, it is often possible to hail a taxi to LGA or take the M60.
Rental car: insane for New York City, can make sense for other areas.
No great options. Good luck.