I have same model car as a daily, its gutless in stock form, and the 4speed just makes it a cruiser not a race car...
extra gear makes it a lot better on highways so if highways are your thing then id swap in a 5speed...
I think the same as you about not thrashing it in 4th... basically I only go fast when necessary... when its 60 its 60, when its 100, its 100, simple...