There do not appear to be any current bonuses for the route you will be flying. You can get up to 1,000 bonus miles by buying your ticket at their web site and using electronic ticket. Electronic tickets can be used on all domestic Delta Air Lines flights except certain Delta Connection flights. This is an extract from their web site:

Take advantage of the SkyLinks Reservations Desk and earn a bonus of
500 SkyMiles for a round trip or 250 miles each way after travel is
complete for each ticket booked! Plus receive an additional bonus of 500
SkyMiles for a round trip or 250 miles each way for selecting
ELECTRONIC TICKETING

Check out their site at http://www.delta-air.com for full details. Hope this helps ...