One thing I have found to watch for if I want maximum quality at the same time as reducing resolution, is to use small integer ratios, like 2/3rds or 1/2. For example, if my original image is 3200 pixels wide, then I could scale it by exactly one-half and get 1600 pixels wide. The result is much, much sharper and better quality than anything close to 1600 but not exactly 1600. For instance, scaling it to 1700 would actually reduce the quality worse than scaling it to 1600, if the original image was 1600, due to fudging and interpolation needed to produce a pixel matrix that are is not the ratio of simple integers multiplied by the original image.
You can see this visually if you are looking at an image at 100% and then scale it down a few percent. Suddenly the image gets softer, but it will get sharp again when you are at a ratio that is a simple ratio of two small integers like 3/4, 1/2, 2/3, etc.
If you are keeping full resolution, then this won't matter. (It sounds like the OP just wanted full size images, but the second poster talked about downsizing.)
Also, if you are scaling down by more than a 5:1 ratio or so, then it doesn't matter what scale you choose because there are so many pixels to choose from that fudging and interpolation doesn't end up making the image softer. So an image that is 320 pixels wide will be just as sharp as one that is 317 pixels wide, if the original was 3200 pixels wide, for example.