I just parked before the weekend on 100th street just off Ditmars. It's right across from the Aloft and from Air Park, so I figured I might have a couple of shuttle options if needed.
Outbound I flew from Terminal B so I walked across the 94th street bridge. About 10 minute walk. On the return I arrived at terminal D. Made sure DW and infant were safe at a place where I could pick them up (departure level). Went down and found the Red Route LGA shuttle bus. I asked where he's going, to which he responded by asking me where I need to go. He went across the 102nd street bridge and dropped me off at the traffic circle. Less than a minute walk to my car.
IIRC alternate side parking was Monday where I parked, which would have made me good for a week and a half if needed.
102nd street bridge is only open in one direction and for vehicular traffic only.
Now let's see
@Dan beat that for plane to no-fee parked car @CLE.
Other than the runway congestion, LGA is my favorite NYC area airport precisely for this reason. Easy and free parking and walk to/from terminal.