Hi katieeldr,
I just returned from a Saturday overnight at the Holiday Inn at the Park (long discussion, but am working in Sacramento and just had to visit at least once); IT WAS GREAT!
First of all, Holiday Inn at the Park IS in walking distance to the park, well, about 10-15 min's on a wide sidewalk next to a very busy street, although walking across the entrance ramp to the I-5 can be a bit intimidating; however, the crosswalk does have a light and is very well marked (and majority of time cars stopped when they saw me standing there). I'm not sure I would recommend the walk for families with small children that like to dart into streets, but it is definitely do-able. The shuttle is available, and costs $2/day/person, but then you're stuck with its schedule.
Technically it's claim to being the closest to the park is not incorrect since it is right behind the park across I-5. You can see the fireworks from the pool area as well as the outside corridors around the hotel where anybody can stand, which is a plus since not all hotels closer to the entrance have outside corridors or areas where anybody/everybody can view the fireworks. However, the greatest decision to stay at the Holiday Inn at the Park is its pool and hottub which is open 24 hrs. Nothing like returning from the park and being able to soak in a hottub at 1:00am.
Otherwise, the rooms were clean, the bed was firm (some might say hard, obviously newer mattress/bed springs, but I liked it), the typical HI bathroom with the sink outside the tub/toilet-area in my room.
The other contributing factor in my view is that because it isn't sandwiched in with all the other hotels, you don't have all the foot traffic nearby; generally, only people staying there are around.
I know this throws a monkey-wrench into your decisions, and you probably won't go too far off as long you stay in a "Good Neighbor Hotel," as they have to maintain certain minimums, but had to let you know my experience.
Whatever you do, don't stress too much about the hotel situation, they each have their own strengths and weaknesses. Enjoy!
-R