OP,
I try not to show my bias (I like LACs), but you sound like the sort of student who might thrive more at an LAC than a larger private university. There are exceptions (Chicago, for instance), but you’ll find many who report that the environments at Ivies and Ivy-likes are filled with large classes (sometimes taught by TAs during the first two years) and professors who are not always focused on undergraduate education. Also, some students at these schools report that though they are kept busy with a lot of work, they are essentially teaching themselves the material (again, because the professors’ attention isn’t always on undergraduates).
Again, there are always exceptions, and certainly there are people who thrive at Princeton, Yale, Chicago, and Dartmouth (I am trying to list the prestige schools where the academic rigor and quality are in synch). I guess I am saying that you might at least look into LACs like the ones that have been mentioned. To be honest, most quality LACs will offer fairly rigorous academics and close relationships with professors. Lawrence U. was one named (by Time, perhaps?) as one of the most challenging schools in the country. Of course, these lists are all over the place and the names of schools on these lists vary.
Still, Reed is a place famous for its rigor and quality (though it is a very progressive environment; a typical progressive like me would be viewed as a card-carrying Republican there). Wesleyan (also very progressive) and Holy Cross (not as progressive but still liberal for a religious school, and it’s not just for Catholics!) are also well-known for being intense environments academically. Really, though, at most LACs the rigor is sort of baked into the cake.