It's not easy to a direct flight from Boise to anywhere, but Southwest will be adding new direct flights from Boise later this year.

I love Southwest....not just because their flight attendants are hilarious, but because the do offer direct flights to probably more destinations out of Boise than any other airline....Las Vegas....Phoenix...Los Angeles....Oakland...Sacramento Denver and Chicago to name just a few, and starting in June, you will be able to fly direct to San Diego check the link for all the info