For maximum cucumber crunch, choose firm, slender cucumbers with thin skins. Cucumber seeds become bitter with age. Slice older cucumbers in half lengthwise and run the tip of a spoon down the center to remove the seeds. Or try hothouse cucumber. These very long slender cucumbers don't have many seeds but cost a bit more.
Rice vinegar is less acidic than cider, white or wine vinegar. Look for it near the other vinegars in the grocery store.