Delta's new 737-800's have 156 seats vs. the 157 of the 727's.

The tube diameter of the 737-800 is the same as the 727, so don't complain too loudly about the width of the aisles....if they make the aisle wider, then they have to make the seats narrower....

The 727 is about 24 feet longer, but the 737-800 has more wingspan which may explain the better climb characteristics.