Doesn’t matter what else you do, never ever again refer to our city as San Fran.
I’d recommend skipping all the walking and getting out on the water. Find a boat trip - ferry, catamaran, speed boat, or anything and head out on to the bay.
Barring that if you are up for a healthy walk, leave your motel and cross Lombard heading North. Walk one block up Buchanan to Chestnut and then take a right on Fillmore. Walk to Marina. If you want to head towards the bridge (west), you are about 1.5 hours at a slow pace from Ft Point (the foot of the south end of the Golden Gate bridge). Alternatively, turn right (east) and walk along Marina turning right on Laguna and left on Bay. If you want to check out Ft Mason you can but I think it is skippable - lots of small theaters and “spaces” and a great art store but nothing super tourist friendly. If you were a hipster I’d recommend going into The Interval but if your kid is just entering college then no.
So stay on Bay 5 blocks (heading east at this point) until Polk, when you take a left, walk downhill 2 blocks and take a right on Beach. Walk up beach a few block until Taylor. At this point you have a decision. Do you want to check out Fisherman’s Wharf or do you want to ride a cable car? If Fisherman’s wharf, take a left (north). If Cable Car take a right (south). Either way about now is a good time to either buy lunch or eat the lunch you have in your backpack.
I’d choose cable car, but that’s me. If you do, line up, pay your money and enjoy your ride over the hill to Market Street, where you can see our world-famous homeless population and shop at F21 and the like.
If you go towards Fishermans Wharf check out Pier 39 (and think again about that boat trip), and eat if you didn’t already then walk along the Embarcadero to Powell where you take a right (south) and then walk up Powell to Lombard. Another decision point - Coit tower or Crookedest street? Tower to your left up Lombard, Crooked to your right, each several blocks away. Either way be prepared for hills.
At this point, you are exhausted from walking, so call an Uber which you cleverly already downloaded onto your phone because someone you know told you it’s impossible to hail a cab in SF. Give them your motel’s address and thankfully let them take you back.
Good luck, have fun, and wear layers.