The tab kit add-on for firefox has many features that allow you to customise the way that tabs look and behave.
Here is how I have setup the various options (tools -> addons -> extensions -> tab kit -> options)
The most obvious change I make is to have the tab bar along the top, and to show up to 4 rows at once (useful while using entrecard).
In this section, I like to have a minimum tab width of 80 pixels, tick all the appearance options.
Here, I disable all mouse gestures, and I like having scrollbars instead of arrows.
In this option window, I make sure I automatically group new tabs, but I don’t like collapsing inactive groups. I also like having ungrouped tabs to the right of the current tab.
And I tick all the options under open tabs by default.