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I'm also trying to find something that basically does what you've requested. The options basically seem to be: touring/commuting tyre with a bit of tread (e.g., Marathon), CX tyre (e.g., CX comp), or MTB tyre with solid central tread (e.g., Landcruiser). The CX option seems to be lightest, although the touring tyre might give the lowest rolling resistance on road, since it's closest to a slick.
Horses for courses I guess. I always found tyres made a difference to my enjoyment. 32c Bonntragers Hardcases (I think) have been my favourite for the city. Or possibly 25c refuse on my fast bike.