I use ACDSEE Pro 3 to resize and watermark multiple folders of photos in a batch every day.
Hold control and select the folders containing your photos.
Watch the bottom right to make sure they are all fully opened.
"Select All Images"
I've done batches of over 30k photos at a time that way.
But...
you'll still have to rename them folder by folder if you want to use different names for each folder.
