Sounds like a pretty good plan (and thanks for having it thought out instead of just saying, "what should we do?"). I don't think it's too packed, remember SF is a very compact city (the whole city is only about 7 miles x 7 miles); if you wanted to you could *walk* from the farthest two points in a few hours.
I'll now throw out a few comments/observations:
1. Consider getting MUNI Passports, they'll give you unlimited rides on all of MUNI (including the Cable Cars which are otherwise $6 every time you board). They come in 1, 3 & 7 day durations ($14, $22 & $28) and I'd say the 3 day might work best for you; although maybe not. Otherwise (non-cable car) fares are $2 and come with a transfer good for 2 hours (90 minutes?). Even when they don't make complete sense from a pure dollar & cents standpoint, there are many intangible benefits (faster boarding, no worry about exact fare or transfers running out, ability to hop on/off on a whim, etc.).
2. I didn't see the Cable Cars on your list and you also might want to do the Cable Car Museum (it's free). You get some history see how they work, etc. It's not that big so it's not like it takes a ton of time.
3. If you want to try & compress things (get more done), you might make checking out Chinatown (and perhaps even North Beach) as part of your first night. The Chinatown Gate (nearest portion of Chinatown) is only about a 10 minute walk from your hotel. A straight walk from there to Washington Square (using it as the proxy for North Beach) is maybe another 15 minutes or so from the Chinatown gate. (See I told you SF is compact.)
4. I'd say you've probably got too much time for Fisherman's Wharf/Pier 39 area. I do think it's worth a walk through - see the sea lions, the views, gawk at stuff etc. - but I think maybe an hour or two is generally plenty; I mean how many shops with tacky tourist trinkets do you want to see (and you'll see them in Chinatown too). Also, you might want to add the Maritime Museum (at the west end of the FW area, Hyde Street Pier); some old ships, WW2 submarine, etc. In my opinion it is about the only thing around FW worth significant time.
5. It's true the GG Park is a large urban park (in fact, bigger than Central Park), but it is still only about 3 miles from end to end (on the long side). You could walk it in an hour or so. If you're inclined you could do this, you could add Ocean Beach & the Pacific Ocean. Its worth noting that the N Judah streetcar runs the entire length of the park a block or two south of the southern edge of the park (which you could use if you got tired, wanted to "speed up" and/or stop & head back to downtown).
Also, there's a commercial cluster in the Inner Sunset around 9th & Irving (a block south of the park near the museums) which has a good selection of restaurants, etc, maybe pick up a picnic lunch & eat in the park? (I recommend Gordo's for burritos, less than a block from the park on 9th Ave.)
On this note, I notice your itinerary doesn't hit on a frequent forum topic, eating! Got any particular desires re: cuisines, budget, ambiance, etc? We can make suggestions.
6. You might be able to squeeze some of the "smaller" things (like the Ferry Building) in as quick side trips from your hotel or on the way back (it's an easy quick MUNI trip from Powell to the Ferry Building either via the metro (subway) or the F Market (above ground, antique streetcars).
That's my $.02 - hope it helps,