+1 Ella Dunn is right. SD is quitte compact, Uber and Lyft are not an expensive option.
Check your Nextdoor app for neighbors who do transport to the airport also. Can be a better rate than Uber's or Lyft.
I use off site indoor parking at Wally Park. They run shuttles and you can park yourself or valet
So, if you want to get to the airport, you have two options: you take your own car or you take a Lyft or Uber from your home. It really depends on how long you are going to be away. If you are away for a long time, several days at least, then I strongly suggest using Uber or Lyft. If you leave your car at the airport, you pay per day. I'm not completely sure what the rate is, but it can get to be costly.
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