Birmingham isn't too bad. When you come out of New Street station down a ramp most of the shops are in a 'block if you turn right, then keep going left you can get back to the bottom of the ramp easy enough. It has the Bull Ring and Pallasades centres too.
Or if you can get to Dudley, there is Merry Hill which I like. It is a big shopping centre with loads of shops under one roof New Look, Dorothy Perkins, Topshop, and plenty of other places for both of you. Plenty of cafes dotted too and as it is under one roof with signs all over the place you can't go too far wrong.
Whatever you decide - have a great day out! xxx