well...just focusing on only, means go somewhere, it suggests a destination. means the movement . I want to give you some examples for better understanding.
1.- let's go out! -Okay! In this case, you can use "走吧" as "okay".
2. -let's go! - go where? -->"去哪儿啊?"
3. [when leaving home to work] you can say “我走了!!” “我去上班了!”. Both are okay.“去” is often followed by purpose, the thing you are about to do next.
4.-how do you go to work? -by foot.(which is hardly possible:) ) you can reply"走着去(上班)。"
5 when you are outside for a stroll and asked by one person "what are you doing outside?" "(我)(随便)走走。"or "溜达溜达" both are equivalent for "I'm taking a random stroll." The tougue here are important.
6. and others like"走着!" “走起!”“走走看看!” “走哪儿去啊?” “去处”(place to live in, a home) are very native usage, I highly recommand you to pay attention to the tongue of this phrases.