Don't move to Munich, they are worse...they still dictate local legistlation and commerce regulation by popular Christian and local out of date custom beliefs.
Berlin has a lot to offer on Sunday...there are now many shops, stores, etc. open on sunday and some until 22:00 or even midnight other nights.
All museum bookstores are open...no admission, obviously.
Obviously cafés, restaurants, bars, clubs are going...Hauptbahnhof is always open, hosting shopping mall with variety of shops. The movies. All video stores I know are open (my fav, until 1am).
If you are looking something a bit more relaxing and peaceful, then the greenspace in the entire region in and around Berlin provides a bit of elbow room...as one pointed out, some spots more hot than others. Biking?
Grilling in the last few spots allowed...easy to organize and just do.
At least once a month, stores like Obi, Bauhaus,
Ikea are open on a Sunday.
the whole "quality of life" bullshit is a moot debate...I feel there should be more open on sunday, allowing employers to employ more people...ask an unemployed person what their quality of life is. It takes time, but it's coming.
I enjoy locally now many supermarkets are open until either 22:00 or even some midnight...it allows people of all schedules, etc to also get their shit done. I am still amazed at all the uncommerce thinking businesses that open between 10 and 20:00...it totally avoids those that actually work and have the surplus income to spend in those stores...what the hell are they staying open for? Bank hours are an old fashion joke. So before you start bitching about the job you work and calling for a social uprising that allows you more hours in the day to run your errands during the day, think about if you would even have the same errands if you didnt have the job. Its an ever-changing world, love or hate it, perhaps old fashion german ideals about opening hours and hours of operation should be updated as well.