MacDaddie-
it ain't that easy. My husband is normal weight but he's 6'2". Even on CO, where I had Silver status, I haven't been able to get us into the bulkhead row. The final indignity was a flight to Europe last year, where we were just behind the bulkhead row, which was occupied by a couple of kids (ages 8 and 10, maybe) with their parents across the aisle. They RECLINED. I don't want to get into the debate we have on the other thread about reclining but, darn it, they had enough leg room to begin with and then took up some of ours.
I think CO would rather give the bulkhead seats to short, lightweight people with higher status than people who need it because of their size. I've found DL, on the other hand, to be totally random. I once got an Exit row seat on a flight where people were waitlisted to get on because the previous flight had been cancelled- and I hadn't flown DL for over 2 years. We took a DL flight from ATL to MCI 2 days ago and 2 exit rows were empty. (We took one of them over.)
But, to be realistic, there just aren't enough Exit row and bulkhead seats to accomodate everyone who could use the extra space- and not everyone qualifies for the Exit row, anyway.