Las Vegas must be sad it is not the weirdest. They try so hard to be ... yet I visited a friend who lives there and it is mainly the visitors that support the weirdness there. Locals avoid the BIG casinos.
Guanajato does have amazing mummies, but apart from that, the town is very welcoming to tourists, not weird.
I have been to about 25 countries and looked for not-your-normal-tourist locations. The WEIRDEST place I went to was:
Luckenbach, Texas (about 50 miles west of Austin)
it had a population of 3 during the week (and 2 of them were dogs), but 200 on weekends.
Basically, Luchenbach is a pub where country music parties hard. I heard they also have armadillo races.
In Australia, driving across the Nullabor is an experience. It has the longest stretch of straight road in the world.
When you drive at night, you see a motorcycle coming towards you ... 40 mins later, you realize that there are 2 headlights, 20 mins after that, you pass the truck that was coming at 70 + miles/hr.
They are about to open a golf course crossing two time zones and stretching 848 miles. (See link below)