The reviewers will be looking at 100%, so images have to be absolutely sharp and have low level of noise at that resolution. Also watch out for color fringing, especially on the second image. As to overall look, both of the images seem a bit flat, maybe tweak curves a bit on the first one and increase saturation on the the second one?
Plus, it always helps to keep in mind whose need you are trying to satisfy when submitting images. Who would want to buy them and what for? If you have at least one positive answer to those questions, then it's a sensible choice.