Fun things to do in DC?

Me & my dad are taking a trip there over spring break. I'm 15, & never been there. What would be some fun, cool stuff to do that we'd both be interested in? He's mostly interested in history, monuments, & museums. I'm interested in mostly those things too, but I also enjoy looking at art and eclectic things. I'm also interested in pop culture from different decades. We'll be there for 3 days. Also, any good recommendations for a hotel? Thanks! :)