List of top 10 must do marathons fyi:
1. Athens Classic Marathon
November 13, 2011 runners will follow in the footsteps of Pheidippides as they track the route of the first Marathon. We capitalize the name because it was from this small coastal town that one man struggled the original 26 miles to Athens — across arid, rocky ground. When he got there he proclaimed civilization was safe, that the Greek army had defeated the Persians. He then keeled over and died. The route is not for the faint-hearted.
2. Dublin Marathon
October 31 runners gather for a decidedly different foray, one billed as the friendliest in the world. The Dublin Marathon is largely flat. It starts at Fitzwilliam Street Upper, and finishes up in Merrion Square North — both close to the centre of the city. Along the way contestants are cheered on as perhaps nowhere else. Spectators feel their pain — and are more than happy to help them kill it with a Guinness or two when the race is over.
3. Boston Marathon
April 18 there's another run blessed by the Irish. It's on the other side of The Pond. The 115th running of the Boston marathon attracts a million spectators a year. The course is fabled — for its beauty and its brutality. Rural Hopkinton is the jumping off point. Then the run winds through countryside and townships before terminating in Boston's Kenmore Square, in the shadows of Fenway Park. But first contestants must conquer Heartbreak Hill — and their own demons.
4. ING New York City Marathon
If the Boston Marathon unofficially kicks off prime time North American runs, the ING New York City Marathon finishes them up on November 6. The Big Apple event may not have the history of its New England cousin, but the competition is every bit as tough. The course is a true five-borough affair, drawing the city together. It starts in Staten Island, then makes its way through Brooklyn, Queens, the Bronx and Manhattan before finishing up in Central Park.
5. Rio de Janeiro Marathon
When it's summer in the Northern Hemisphere, it's winter in the Southern. Rio is the setting for perhaps the planet's most sensuous run July 17. The route — which visually rivals any — sambas through city streets. It starts out in Reciero, and finishes up in Flamengo — ocean to the left, and mountains to the right. Along the way runners weave through Praia da Reserva, Leblon, fabled Ipanema and Copacabana — as on-lookers urge them on.
6. SSQ Quebec City Marathon
Since its start in 1998, the SSQ Quebec City Marathon has welcomed 48,000 people to run along the shore of the St. Lawrence River. On August 28, 2011, the 14th one will occur as the biggest international sports event in Greater Quebec City. Whether you partake in the marathon, the half marathon, the 10k race, the fundraising Health 5k, or the kids run, there are plenty of ways to celebrate running, walking and fitness in general in Quebec City.
7. Virgin London Marathon
Lots of races in lots of places this April make it tough for top competitors to choose. One of the very best is in London, on April 17. Triple world champion David Weir returns home, aiming to win a fifth men's wheelchair title at the Virgin London Marathon. The marathon follows a comparatively flat course along the Thames. It's the only marathon on the planet that begins in the Eastern Hemisphere and crosses over at Greenwich into the Western.
8. San Francisco Marathon
Lots of marathoners find their heart in San Francisco. July 31 is this year's date. The course is out of a guidebook. It begins on the Embarcadero, passes Fisherman's Warf, the Marina and crosses Golden Gate Bridge. Runners return across the bridge, pass through the Presidio and through Golden Gate Park. Then it's on to Haight Street, and through the Portero and Mission Bay Districts. Look up and behold the Bay Bridge. The finish is just ahead.
9. Bank of America Chicago Marathon
Autumn leaves should be falling by the time October 9 rolls around. This is the Upper Midwest, and terrain is flat. Runners can flat out fly. They like the venue because they can push their personal best on the closed-loop course. It starts and ends at Grant Park, winding through a number of Chicago's neighbourhoods. During the first three miles, the course passes through downtown Chicago. Eventually it heads north, along LaSalle Street.
10. BMW Berlin Marathon
Berlin is a biggie, attracting top talent from around the planet to this reunified German capital September 25. The run starts and finishes next to the Brandenberg Gate. The course is comparatively benign, and eminently historic — passing by places such as the Reichstag and Berliner Dom. Like Chicago, the flat German topography spawns some spectacular times. Weather permitting 2011 should be no different. Given the one-time division of Germany, Berlin's marathon takes on special significance.
(Editing by Paul Casciato)
http://uk.reuters.com/article/2011/04/01/uk-travel-picks-marathons-idUKLNE73003520110401
The list is from a two year old article but I imagine the dates are close to the same.