Unfortunately the seats in Section 328 Row 11 will be the standard seating width, and are not padded. You are correct that the armrests do not extend out all the way to the end of the seat bottom when in the sitting position, so that will leave slightly more room on the sides.
For wider padded seating, you will want to look for seats in the club sections (C106-C115, C132-C139, C206-C214, C231-C240, C307-C314, and C332-C339). These sections feature wider seats than the rest of the stadium, more legroom, and padded seats.

Club Seating Locations at AT&T Stadium
The Club sections offer the best place to find wider, padded seating at AT&T Stadium