Growing up in Wyo, and my sister going to school in Spearfish I highly recommend going about now until maybe the 2nd day of event. I like open areas and no traffic.. I would never be there the whole week just way too many people, it freaked me out the last time I was there in 03, and how much Rushmore area has changed.... Have fun and be safe, if you see some kid on dirt bike giving the HDs the finger( that was my play). I grew up 2 hours east of Yellowstone, we had tons of bikes pass thru in the summer...