There have been a ton of hotels built in the last decade or so, mostly chains you'll recognize, don't know any more than that. There are some B&Bs in town that I'm told are really good, period buildings appropriately decorated and furnished. Again, it might already be too late for some of those for the July 4th weekend.
Gettysburg is a pretty small town. It's near US Rte 15 and US Rte 30, but it's all 2 lane roads into and through town, so traffic can be really, really slow.
There are some other small towns in the area that you might also consider walking around. Hanover, PA is similarly old and there are some really nice antique shops in town. Frederick, MD isn't too far away, I always liked the place. Also an older, historic town, but it has a small but lively restaurant, arts and antiques vibe downtown. Frederick does a really nice 4th of July celebration. A number of different musical performances, and the headliner is usually someone pretty well known, all for free. One year I saw the Smithereens there. Lots of food and activities, very good for kids.
Gonna buy a fast car, put on my lead boots, take a long, long drive
I may end up spending all my money, but I'll still be alive