Good afternoon Lee.
Sorry I'm late coming back to you.
Certainly a dark suit will be more than acceptable.
I have just done a solo trans Atlantic crossing on Queen Mary 2 - my wife couldn't make it and there was a rare bargain price.
Without my wife on board I wrote and published a daily blog...
https://solentrichardscruiseblog.wordpress.com/2013/11/23/solo-trans-atlantic-live-blog-day-4/That's the link to one day, the rest are easy to follow.
You will see I was upgraded to Britannia Club. They are all high staterooms on 12 Deck.
I would suggest that a Princess Grill Stateroom would be very good or even a standard Balcony and dine in the lovely Britannia Restaurant.
Hope that helps.
Richard