A different angle on the question of high-lexile books is to remember that this is but one measure of reading level (and much more hotly debated within the field than it might appear from the marketing machinery). HighIQ, you are obviously a very capable reader, with access to essentially anything you want to read--so read by interest and curiosity, rather than lexile! Lexiles were developed as programmatic and instructional aides for teachers working with the K-12 population (and don't forget, selling their assessment and instructional tools!). The goal line for both Lexiles and Quantiles is college-readiness. You are well past that stage at this point, with ample tools for reading comprehension, so lexiles are really not functionally relevant for you personally (or for pretty much any of the adults on this forum!).
Read because you are interested in the content, or the artistry of the language, or because you want to stretch yourself with a variety of perspectives, or just because it's pleasurable. But don't feel like you have to "challenge yourself" with regard to reading level.
