The problem with the ultrawide lenses is that you cannot use filters with them, as it's Springtime when you're going the sun will be lower in the sky, in Summertime when the sun is high there's not such a problem, of course you might want to photograph the Northern lights, in which case a wide angle is a must. Glare off snow can be an issue, unless it's overcast even f/2.8 is going to be too much, and you'll want to stop down to get the DoF anyway, at night very dark so flash is going to be needed for portraits.
If you want to take setting sun pics then you'll need a reverse ND grad, remember that if you really want wide angle shots you can always stitch them together, but you cannot post process the effect that filters will give you, and lens flare can ruin shots.