Reusing same 2D Environment in different levels

Hi,

I am developing a 2D game by using Unity 4.3. I have one environment which I will produce multiple levels on.

On each level;

• Some new design elements will be added

• Number and start locations of enemies will be different

• Some new type of enemies will be added

• ...

I searched for best practices on internet but the only advice I could find is using the same scene on every level and making the above changes programatically. This is also possible for me. On the other hand, I prefer using editor tools to add items, changing their locations by seeing instead of handling everything on code level.

Another option is developing different scenes for every level. Then, if I want to add/change something which is same on every level then I need to update every level one by one.

Any opinions/best practices will be appreciated.