I think this is one that you'll be best to find out for yourself Brucey!
You've identified multitude options - all have their positive and negatives.
My one bit of advice is to not bother with Weekend First on such a short journey - it's unlikely that you'll get any 'added value' except maybe the off chance of a cup of coffee and some snacks. Oh, and 30 mins in slightly nicer accomodation!
I'm not 100% sure, but I think the Pretendolino has been retired from service now that Virgin have two brand spanking new Class 390s in service.
Two 390s? I thought they were only allowed one of the new 11-car sets (and even then it has to be run as 9-car when in public service) until the start of the new franchise?