My DEN-OGG flight on Sep 15 appears to be on what United calls version 3. I'm currently in 39B (row 39 is 2-4-2 layout). The only other E+ non-middle seats available are 39K and 40D. 39K shares the same problem as 39B which is possible conversion to a middle seat if the aircraft is changed. On the other hand 40D has no underseat storage -- then again, I don't see how 39B or 39K have underseat storage even if they're not flagged that way.

So ... change to 40D knowing I won't have underseat storage but at least I know I'll be on the aisle instead of middle?