Southee needs to pick his balls up and charge into the crease - he bowls like he is there for a long time, not a good time. Milne would be good, and I'm a big fan of Ed Nuttal at Canterbury.
Moving Guptill down the order wont solve anything - you'd just then expose his sharkness against spin. He either needs to eliminate his glaring shortcomings, or be moved on.
Having said that........is Raval really >> than Guptill? And it's not as if Latham has done much.....the thing is, both openers do just enough from time to time to keep them in the team.
I'd need to see more of Raval before dropping him in - there's always a tendency to big up the guy who isn't in, only for him to crap out when he gets in. The Matthew Sinclair Syndrome