Thnanks to everyone for their thoughts so far;
I would not restrict your trip and shooting to moonless nights..... When the aurora is good you will see it with or without the moon being up. Photographically I've become more entranced with shots with the moon used to lighting the foreground - it gives the pictures some more depth to me.
This is an issue I hadn't considered much.
I do have two concerns though;
Firstly, given the expense of the trip, seeing the Aurora is more important than photographing it, so if there isn't a 'good' aurora not seeing anything at all because of moonlight on a marginal night would be very disappointing.
Secondly, I'm not convinced that too much foreground fill looks 'right' I actually prefer the balance of your second shot, it more how I imagine the Auruoa to look in real life. Of course that may change when I've seen it.
Probably among the best person to ask that question is: http://focusonnature.is/
There's a few locals I'll contact nearer the time, it might be nice to have a guide/shooting companion for one night and give the rest of the family a break ;-)
It is better to set up your base in the north (eg. at Mývatn) and be flexible enough to drive out into the wilds at a moment's notice. Another option is to base yourself in the south near Hella (but my preference would still be the north).... The best displays were after 11 pm.
I'm certainly keeping my options open, but visiting the north wouldn't be my first preference. Internal flights aren't cheap and the drive up there from Reykjavik is pretty long and tedious enough in summer. Also there's less choice of accommodation, but if that's the only area with good weather we'll get up there.
First choice is working out from Reykjavik for a couple of nights, then moving along road one eastwards. We know a good place to stay at Hveragerdi, but may go much further out towards Hofn if conditions are good.
Any further thoughts very welcome, especially with respect to how different weather conditions might be between Early Feb and late March.
Paul