I grew up in the DC area. It is a mob scene. Post 9/11 security is absurd. I haven't been in a long time because I think it is too much hassle.
That being said, if you chose to come remember that DC is hot and muggy in July. It will be uncomfortable here, especially for someone from Michigan. Your best bet is to take Metro downtown, cause you won't be able to park. Get downtown early in the afternoon. Make use of military band concerts or other free events earlier in the day. Bring a picnic and be prepared to grab a spot early. Early can mean 2 or 3 in the afternoon... then sit there until 9 for the show to start.
See why we don't go anymore?
If you can find a river cruise it will be expensive and likely still hot, but at least you will have a good view of the fireworks.
Unless you want to go to DC anyways, I wouldn't undertake a trip like this.