Yeah, a 24' ladder will let you access that taller section of roof safely, even if you have to approach it from the side or rear elevation. there is almost always a slope that can be accessed from a 2 story ladder.
I got the Werner with the adjustable legs and really like the stability regardless of terrain. Check out that link, I got a 24' and a 16' with the adjustable legs.
Also check out this link for the "Walk Through" which will add 3' to the length of any extension ladder. I really, really like this thing and use it on my little 16' ladder every time I go on a roof, so I don't have to step around the side of the ladder to get on the roof. It adds some weight to the end of the ladder - but still not nearly as heavy as a fiberglass ladder.
I wanted a 2 story ladder, and was debating a 28' or 32' for those times when the house is on a raised foundation and a 24' might not be enough. The extra 3' on the walk though addresses that issue, and you can leave it off if you don't need the length. But when I am 2 stories off the ground - I like to walk through the center of the ladder. With cougar paws, and if it is bad-ass I use rope and harness.
These are on the ladder rack with a little Giant inside the van for getting in those tight closet attic access doors. Pull off one of the sections so the narrow part can poke into the attic - some of those older houses are a challenge to get into the attic and find the leak.