Realistically, the only thing Silver gets you is a free bag. Gold gets you skypriority benefits at the airport and for boarding, and also T-3 day upgrades vs T-1 (which are relatively useless).
With T-3 you'd have a decent shot at C+ seats depending on the route, and occasionally a first upgrade. But, if you're not going to fly DL much next year to enjoy the benefits then don't bother.
Also if you are located at a major hub like ATL/MSP etc then its not going to be much of a difference due to the large higher level elite presence.