Is there any other map need to be looked into for better idea.
Yep. A good old fashioned paper map. Google just offer their top 2 or 3 choices of what they think is the quickest, but there always far more options than those. A paper map will show you terrain, small towns and much more, giving you a much bigger picture. Once you have studied the map you can always reload Google and drop and drag the blue route line with your cursor to experiment with your options.

You also have the RTA Map centre in the Members section in the tool bar above which you can use to plot distances and find attractions along your route etc.