Re: zone scale
If you care about metric quantities, make sure the scale you choose has a readily accessible lb/kg switch. I accidentally bought one that was factory set to pounds, the kg button was on the bottom, and it didn't remember the setting when you powered it off. Fortunately the store had a good return policy.
(The scale was a Salter, which is usually a decent brand. Apparently they gave the designers of this scale a little too much leeway.)