Need help planning/upgrading

Hello all, I'm a regular guy with a modest budget and "upgraditis". Fortunately, I recently discovered Audiogon and reading through the discussion posts somehow soothes my continual need to tweak my set-up. I'm sure many of us, myself included, have spent too much on tweaks or minimal upgrades--like putting banana plugs on speakers just for the heck of it; buying a "better" hdmi cable; or prematurely adding affordable, yet inferior, sources, components, etc. And, I think my wife is going to divorce me if she hears the white noise from the YPAO set-up again (for the tenth, make that eleventh, time this week).

I'm reaching out to you all because I want to be pleased with each (future) purchase without thinking, "Gosh, what was I thinking when I bought that AVR, and why didn't I plan better?" That said, I'm really just seeking some advice to better my current set-up so that in a year or two I'll be content with my purchases.

Right now, I'm about 50/50 music/HT. But, each time I upgrade something, I care less and less about floor-shaking bass and more-and-more about a breath approaching the microphone or the crispness of a guitar strum. So, with those things in mind, my modest set-up is as follows:

Yamaha RX-V863 (used as preamp for 2-channel with amp section powering the center and rears for HT)
Bel Canto s300 with Shunyata PC (used for front L/R)
PS3 (used mainly as BR source, but also for CD and very little streaming audio)
Airport Express (for the streaming audio)
Def Tech Mythos ST (L/R)
Def Tech Mythos Nine (C)
Def Tech ProMonitor 100 (Rear)
RGPC 600s
Misc. (TV, DVR)
Cables - Speaker cable and IC's are Monster; PS3 is HMDI=>AVR; AVR is RCA=>Bel Canto s300

I just kind of feel stuck, and don't know what to do next. My budget is around $1k right now, and probably around $300/month gong forward. Thanks in advance for any advice.