For legroom, and for a couple traveling together, you can't beat 19D and E on the 757. You will have to put everything in the overhead bin, and it may get tricky as overhead bin space is limited in that part of the plane (overhead bins don't even start until back over row 20 or so), but it is totally worth is for tons of legroom and the fact that in any other seats on the plane you'll have a third person sitting with you.

On some configurations of the 757, there is some "extra" overhead bin space just ahead of row 19 but behind the business class cabin. The FAs often guard it jealously and won't let you use it during boarding (presumably to save it for business class passengers who may need it), but for something like a small purse especially, if your wife just holds it in her lap during boarding, when the FAs come around during final safety checks they will likely put it in those overhead bins at that point.