I don't want Smith to regenerate at the end of the anniversary because that episodes is about the past, IE the 10th Doctor, Rose, the Zygons, and the 8.5th doctor. The 11th Doctors regeneration should be centred around him. But I would like more than a small cameo of the twelfth doctor. Why we get series 8 in fucking August I don't know. What is it with bastard Moffat and his long gaps? Series 8 should start in May at the minimum, we basically go through the best part of the year before we see doctor who.
But in the xmas special, I'd like about at least five minutes with the twelfth doctor. Or maybe Smith regenerates about three quarters into the episode as we've had a doctor regenerate at the end or beginning of an adventure, but never in one. Would be interesting. But I'd like the vast majority with Smith still. But instead of waiting for the end to see the 12th doctor, I'd rather enjoy the episode for what it is instead if be desperate to see a couple minutes of the new doctor. That's where I feel I went wrong with End of Time. I just kept thinking "is he regenerating yet, is he regenerating yet?"
As for the actual episode itself, would you guys rather have a classic villain recurring villain, or a completely new one?