I have a 25ft pole, and it reaches every window on my round, including all 3 stories.
On some 3 story houses it is at its absolute max, so I would go for a 30ft as advised, given the option.
My 25 ft pole is fibre glass, and when fully extended, its damned heavy, so a 30ft would probably finish me off. Maybe buy a 25ft fibre glass to get you started, and invest in a longer carbon pole like the SLX from Gardiners Pole Systems once you get established a bit, which is exactly what I am doing.