A bakery would be nice. A real traditional one which can make all the kind of Breads, yes German for Europeans and Americans but why not but also French, English etc... 

 But food again? Is it really a good idea?

For the mattresses I am sure that IKEA will come soon in Qatar and you will have all the mattresses you need and want.

To me the best ideas are the books, books and books...

Then yes it really depends on the location.

Is the shop open now?