I find Irfanview to be pretty sophisticated for most bulk work. You can set the longest side to a specified size or have it reduce or increase the width and height by a given percent. You can select whether you want a resample or resize and whether to increase the size of smaller images.
You can send the resized images back to the same folder with various rename options, the best of which is probably to just add numbers in front of the resized images. If you always follow the same protocol you can easily know which are the resized images and simplify your folders.
A couple of things I really like about Irfanview are the ability to determine your thumbnail size and the ability in the newest version to include sub-folders in the thumbnails.
By the time Photoshop opens I will have the thumbs selected and into the conversion in Irfanview. I don't know whether it is faster for the actual conversion, but it is a lot faster getting started.
Once you get into actions Photoshop is a lot more sophisticated. But for sorting and simple bulk work Irfanview is hard to beat.