ZMB, 

It is difficult to give that advice, especially given the small sizes, but I would suggest picking images from different subjects: one animal (one of the koalas, for instance), one travel (maybe a less ordinary destination), one landscape, one macro (you have two interesting images of green leaves).  Hmm, how many images does IS require?

Anyway, pick images that are sharp yet not oversharpened, with very low noise, well exposed and with good lighting. 

One personal remark - maybe sites don't bother about that at all - but I noticed your architectural photos are generally too tight in composition, sometimes cropping the top of a tower or something. 

Regards,
Adelaide