That’s how it cur­rent­ly looks like on my ma­chine.

1. I’m used to have the title of a page dis­played in the title bar, so I pre­fer to go with that.
2. Since my screen is wider than the 640 px of this ex­am­ple pic­ture, there is ample room for both the ad­dress field and the search field, so I see no rea­son to hide the menu bar.
3. I could give the back-but­ton and the for­ward-but­ton the or­bital look and feel, but to style just these two tiny but­tons seems a bit point­less.
4. My fa­vorite book­marks are of two kinds: of web­pages I have al­ways open in tabs (so I sel­dom need their book­marks), or of the front pages of search en­gines. So using the search field, I don’t need a fa­vorite book­marks bar.
5. Using some user­Chrome.css, I made the cur­rent­ly se­lect­ed tab high­light­ed in yel­low, like I’m used from Orbit Clas­sic.
6. I also styled the cur­rent­ly hov­ered-over tab. With Col­or­ful tabs, I gave the other tabs a de­fault color that match­es the per­sona I have cho­sen; which I se­lect­ed to fit with Win­dows 7 Aero.
7. I ur­gent­ly need the ad­dons bar to be open all the time, to dis­play the HTML Val­ida­tor, to give me that smug feel­ing of su­pe­ri­or­i­ty by dis­play­ing all the er­rors of other peo­ple.
8. I hid all the icons of those ad­dons I sel­dom tweak (like Ad­block Plus or Grease­mon­key) – it’s suf­fi­cient if I can ac­cess them via the menu bar. Un­for­tu­nate­ly, KeySnail isn’t up­dat­ed yet to the new addon bar in­stead of the old sta­tus bar, so cur­rent­ly, I can’t get rid of its icon.
9. Since the addon bar is al­ways present, I can uti­lize its un­used space by dis­play­ing sta­tus mes­sages with the Sta­tus 4 EVAR addon. I also got rid of the un­nec­es­sary close but­ton.

So, I’m quite con­tent how my new Fire­fox looks, and don’t see how I could sub­stan­tial­ly im­prove it with a cus­tom theme.

Postscriptum:

With a tiny bit of code in my userChrome.css, namely…

#keysnail-statusbar-icon {
    visibility: collapse !important;
}

… I even got rid of the old Keysnail statusbar icon.