Never Summer Infinity - excellent all around board. Would hold up well in the backcountry, long lasting.
Roxy Eminence - a more aggressive freestyle board. This would be a good option if your wife liked the feel of her B-Nice.
The B-street is a good board, but it's pretty soft for backcountry. It really throws the rider around in choppy or rough conditions.
The Cadence is another popular choice if you like Arbors.
Burton Feelgood - similar flex to the Infinity. A very popular board.
Check out shayboarder.com for tons of reviews.