I like the Sublime Text 2 default color scheme Monokai alot. The only problem is the tab colors, the selected tabs and the rest of the tabs all look the sam
You need to dig pretty deep into theme customization to do that:
Since your theme is Monokai (medium-dark) go to "Packages/Theme - Default/Default.sublime-theme"
From lines 528 to 531 are your answers...
Either you hack by changing tint_modifier or layer2.opacity
OR
You go right at "medium_dark_unselected_tab_bg2.png" and try changing it by "light_unselected_tab_bg2.png" for example.
Either way I recommend you using Soda Theme! A really great and easily configurable theme too!