<p>Since you asked, I'll add a few thoughts:</p>
<p>CalTech - very hard to compare to the others. It's an extremely self selective group of students, who join an intense community of tech/engineering/hard science scholars. Very research intensive. I'm tempted to argue that there's little difference between grad and undergrad there. One big community</p>
<p>Stanford - quite focused on undergrad education. Raised $1 billion plus for undergrad education. Offers superb academics then adds university-wide ploicy which allows undergrads easy access to faculty members, to do advanced research, independent studies and get consulting gigs (advised by senior faculty members). In my view Stanford has the best academic balance [hard sciences, social science, humanities, engineering, arts, professions] and the highest levels of excellence of all the top schools. Extraordinary momentum as an institution (top academics, great brand and global reach, #3 endowment). The only clear rival to Harvard.</p>
<p>MIT - similar to CalTech; very self selected student pool. Extremely high quality. MIT loves all its students, but I think it again focuses a bit more to grad students/processes.</p>
<p>Duke - great school, but I can't really speak in a detailed manner to the institutional divide between grad and undergrad.</p>
<hr>
<p>Modified listing:</p>
<p>Tier I (school oriented around undergrads as much as, if not more, than grads) - ranked by academic excellence, breadth, extracurric opps for students, global reach and diversity of students (across all measures)</p>
<p>Yale
Princeton
Brown
Dartmouth</p>
<p>Tier I.5 (special grouping, b/c these schools are so unique, narrowly focused and hugely dominant in their academic sectors)</p>
<p>CalTech (gets the edge b/c of endowment + research funding resources per student, academic breadth, faculty firepower [awards, citations, etc])
MIT</p>
<p>Tier II (slight to material skew towards grad schools, Research (with a capital R), but all still offer great programs for undergrads)</p>
<p>Stanford
Harvard
Penn
Columbia
Duke (I will admit I have the least knowledge of Duke among all these schools)
Cornell</p>