What thickness mousepad should I get if I have a bumpy desk or use a wrist rest?

Get a 5mm mousepad. That thickness smooths out small imperfections and keeps a wrist rest from feeling like you’re hovering over a cliff. Most basic cloth pads are 2–3mm, which won’t hide a dent or seam, but 5mm foam absorbs unevenness so your mouse tracks clean and your wrist rest sits flush. Thicker than that (like 8mm) feels spongy and lets your wrist rest sink in weirdly.