I think you're overstating the difficulty of Seasoned and Reasoned, both are comfortably undergraduate texts (though Reasoned is a challenging text if it's your first time with that style of programming). We used to teach Seasoned to high school students (advanced high school students, but I'd put them on par with motivated 1st/2nd year college students not more advanced than that). I'd agree with the other three, though, they are advanced texts.