> Are their any services that provide usage figures for any of these Dapps?

The closest I've seen to this, eg. an Alexa.com/AppAnnie for Dapps, is https://dappradar.com.

It measures DAUs, transaction counts and daily/weekly tx value (in ETH) across many Ethereum smart contracts. It's not perfect but does provide a decent standardized view of some Dapp usage/traction.