MY FAVORITE!
When my husband and I travelled to Vegas together for the first time I was literally shocked he didn't know about the downtown. Fremont is my favorite! The Fremont Street Experience is free, fun, and very memorable. Plus, when the screen isn't playing its show up above, you can look around you and there are costumed "celebrities" EVERYWHERE. If you don't want to tip them to take a picture together, try a perfectly aimed "selfie" with them in the deliberate background.
Food is good on Fremont. Drinks are cheap. Streets are packed. There are stages with live performances, zip lines, and I even saw a motorcycle ball of death once. ONe of the greatest things I've ever seen live! Plus, this area is rich with history. I've only stayed in a downtown hotel a couple times. Stay on the strip, but take a cab to Fremont and enjoy the experience.