Let’s get off to a flying start with the Garmin Velothon Marathon. Amazingly this is its fifth year but it has already established itself as the second largest cycle race of its kind in Europe. The route will take in loads of the big tourist sites in the city like Brandenburg Tor, Potsdam Platz, Tempelhof Airport and Eastside-Gallery so if you want to pick a good spot to watch then these places will be ideal.
Also remember that large numbers of roads will be closed so your best bet will be to use the U or S Bahn, along with the rest of the population. The finish line is on Straße des 17. Juni and the atmosphere here is bound to be electric.