The elusive right combination
But since then we've held combined Carols and Holy Communion, an earlier children's service (as early as 6 PM if I remember correctly), and Holy Communion at various times, including Midnight Mass (starting at 11 PM). At least one or maybe two years the services were close enough that it was better to have a parish supper, rather than have people drive all the way and back again -- some live quite a ways away.
The one problem with Midnight Mass is that it is difficult to leave at half-past midnight or so, drive home, sleep too few hours and be up and back for the 10 AM Mass.
So this year we're holding Carols at 8 PM, followed by Holy Communion.