The Back Street Boys of Classical??

I have recently started piano lessons and theory with a wonderful teacher who is remarkably intelligent and has decades of experience playing and composing. When asking me about my taste in music, I think I mentioned Stravinsky, amoung others, from a basket of jazz, pop and classical music that I have enjoyed. I guess I need to be humbled as a student as I was a little embarrassed when he used the expression "salon composer", which I took to mean popular with the bourgeois but not taken seriously by musicians. An additional faux pas of mine was thinking that Vince Guaraldi should be found in the "jazz" section of Tower Records. Could someone educate my a bit more about classical (In the Tower Records, not historical sense of the word) composers? Who would be considered the N Synch of their time? And which composers have really endured as as worthy and challenging for people who really understand music? I realize this is somewhat subjective but hopefully will inspire lively debate.