You should visit Downtown Vegas at least once in your life. This is old Vegas. If you are into gambling, then you definitely should be here. You will also find cheap booze & cheapest souvenirs in town here. I suggest arriving in the evening for the Fremont Street Experience.
Downtown Vegas is not walking distance from the strip, so you will have to figure out how you want to get there. I had a car, so it wasn’t a problem. You won’t need to make a list of things to see, as there are awesome maps here, that tell you everything you need to see & it’s all in one area too.
So grab a drink, play a game, buy some souvenirs & enjoy the Fremont Street show.