For travel over the July 4th holiday, fly nonstop from Seattle to San Diego for $317 roundtrip on Delta.
I found flights departing Seattle on Wednesday, July 3, returning from San Diego on Saturday, July 6
You'll find lower fares available for non-holiday travel.
This fare includes a carry-on bag plus a small personal item. The first checked bag costs $30 each way.
Advance seat selection is allowed for this Economy fare.
A Basic Economy fare is $277 roundtrip, which does not include advanced seat assignments and does not allow upgrades/ticket changes. A checked bag is the same $30 fee each way.