From LaGuardia website:

Subway/Bus Combo to LGA - Cheapest Method
With a little exercise, you can travel to La Guardia Airport for just $2. There are two basic ways to do this - the first is to get to any New York subway station where you can make a free transfer to the M60 LaGuardia bus - This bus runs across 125st in Manhattan and then into Queens and up to La Guardia Airport - the most optimal subway stations to get this bus are Astoria Boulevard in Queens (N and W lines) or one of the three 125 Street stations in Manhattan that serve 4,5 and 6 lines, 2 and 3 lines or the A,B,C,D lines. If you exit one of these stations you will find an M60 MTA bus that is both regular and reliable. Many of our subway testers have found the Astoria Boulevard route is the best, but that assumes that the N and W lines are running properly. This method of getting to La Guardia Airport will take about 45 minutes from midtown Manhattan, longer if you use one of the more westerly subway stations.

If that section of New York is having problems (The 2006 power outage in Queens that lasted 5 days played havoc with the New York Subway system) a popular alternative is to take the 7 train out to 74th Street in Corona (it has escalators, and the E, F, G, R, and V trains also stop there), go downstairs, and ride the Q33 bus to LGA (also a free transfer with your MetroCard). It, too, takes about 20 minutes after your 15-minute ride on the 7 train. If it’s a weekday, remember to take a local 7 train, as express trains bypass 74th Street. Keep in mind, however, that if you’re going to the Marine Air Terminal, you need to take the Q47 bus from 74th Street, since the Q33 does not stop there.

You’re right to point out that streetcars have to be a real, practical transportation option, which I am calling for here. I’ve lived in cities where they have worked, however those were in Europe where there was less ground to cover, denser traffic, and streetcar specific lanes. Streetcars could get through where buses couldn’t. The optimal option would be a subway, but then we’re talking about a huge cost increase.

Regarding streetcars over buses, one benefit I see is that it is easier to predict the routes of streetcars over buses. When you see tracks somewhere you know that you can get there by public transit. It seems more usable and riders are more confident taking them, leading to greater usage. This may be psychological – why not just teach everyone the bus routes? – but it is that reason why rail attracts more people than bus. Just look at light rail versus bus use in Dallas. This paper outlines the phenomenon:

http://pubsindex.trb.org/document/view/default.asp?lbid=308484

which you can read here:

http://www.heritagetrolley.org/articleTennyson.htm

From Seattle:
South Lake Union accident takes red streetcar out of service
http://seatrans.blogspot.com/2008/04/streetcar-crashes-again.html
“The red South Lake Union streetcar has been taken out of service after a midday fender bender.”

and:
“When we have a desperate need in Seattle for real mass transit, and for fast and reliable service, it’s depressing to see the city promoting streetcar service that is even slower than buses. Transit can be an amenity, but it will be a more effective amenity if it also provides a transportation function. We can’t afford to put all of our money into making yuppies feel more cosmopolitan, and making their condos more upscale.”
http://seatrans.blogspot.com/2008/04/streetcar-crashes-again.html

http://renegadebusdallas.com/2009/06/18/buried-streetcar-lines-update/

Also, if you are stuck somewhere after the buses stop running, why would streetcars still be operating?

I strongly agree that Dallas proper could use it’s own secondary system, immune from suburban “input”, but I just don’t see how streetcars help.

I hear you about making light rail work better for urban dwellers. I’m spoiled now living close to the new Green line plus Blue and Red lines, so I can get to most of my favorite spots pretty quickly from light rail. But I would love to take a trolley all the way to Ross & Henderson, Lower Greenville, or from Pearl to McKinney Ave.

I don’t know why Dallas hasn’t figured out how to make street cars work for urban dwellers or tourism. Recently, I ran into a European couple looking desparately for the trolley at the Pearl light rail station. I suggested to them that they could easily take Bus #21 to McKinney Ave, but they were insistent on seeing the trolley as an attration. I drew them a serious map to get to Akard & Ross to catch the trolley.

Leaving these folks, it made me think how great it would be if we had a trolley system to all major attractions in the city core. A recent visit to San Antonio reinforced my feeling that this can be great for city inhabitants and visitors. We used the trolley bus in San Antonio alot to get to many of the restaurants, bars, and attractions which weren’t within walking distance. Kudos to San Antonio. Just wish I could be singing the praises of Dallas on this issue.