I'll confess I've become a bit of an Opera fanboi over the years - and one way I've found to maximise the screen real-estate is to merge the main bar and address bar, and rather than having a seperate search field, search from within the address-bar.
I use the menu bar as normal, the next row contains a stripped-down main-bar leaving loads of room for the address and zoom fields, then tabs below that.
If you do it that way, on a 19" old-style screen you lose barely an inch off the top, and it's easy to navigate 40 or more tabs because they've got automagic thumbnails when you hover them.
If you were doing something graphics-heavy you 'could' turn it all off bar the tabs and put the browsing controls in the right-click context menu instead - it's not difficult to make the interface exactly the way you like it.
Looks like what both Mozilla & MS need is to get the config-files sufficiently well organised that ordinary users aren't scared to fiddle - maybe all it needs is a 'mend me' button to give novice fiddlers the confidence to try... it's really not difficult for even 'non-geeks' to make the browser they really want, the trouble is, nobody but Opera seems willing to tell them that and show them how... MS don't seem to trust their users, and Mozilla still only works as and when it feels like it - maybe because it wasn't broken, then a thousand people fixed it until it was?
Paris - because even she could make her perfect browser with Opera.