This is the best approach. (The "a staff member will approach the uninitiated customer whose laptop is open for more than a couple of minutes with a gentle but firm request ‘to finish up what you’re doing and close the laptop, please,’ approach is the worst. No sign, no explanation--just a demand.)
> the Rose doesn’t provide electrical outlets; a dwindling battery should be a sign that it’s time to go
This is also fine, albeit ineffective against my MacBook Air.