I suppose logically you could "see the fireworks" from anywhere reasonably close. It's not like DC has huge skyscrapers that block your view.
But if you want to see any of the stuff on TV with the concerts and be right in front of the fireworks, public access to the area starts at 10am and people camp. I honestly think you won't be able to get a decent spot to see/hear any of the concert if you don't get there until 4. Also be aware that the Smithsonian Metro Station will likely be closed for most of the day due to security so don't count on being able to use that.
Not that I want to intentionally contradict you. But just wanted to let others be aware that our plane did not land in DC until 4:00 on July 4 last year. By the time we made it to our hotel and then had a car drop us off at the National Mall area, it was around 6:00. We were able to get through the security line in less than 10 minutes, were able to freely walk around the area around the Washington Monument. Got something to eat at a little stand. And there was PLENTY of open space around the Washington Monument at that time. After we ate, we wandered closer up the hill to the Monument and plopped down to wait for the fireworks. We were able to lounge on a blanket that we had brought, and did not feel overly crowded at all.
From what I had read beforehand, I was expecting wall-to-wall people and barely being able to stand and move. That was not the case at all. Yes, there were a lot of people, but we were spread out and everyone was able to lay and/or sit down on the ground.
That being said, we were NOT in front of the Capitol building where the 'official' show that was broadcast on TV was. So, I do not know how crowded that area was.
FYI, the fireworks are actually shot off just in front of the Lincoln Memorial, around the Reflecting Pool. So, our view from the Washington Monument hill was really great. And there was a stage set up between the Washington and the WWII with some patriotic music. We could hear everything just fine, and could just see the side of the stage from a distance where we were. That was fine with us. The music from the stage was being played on a PA system so it was loud enough for us to hear and enjoy.