I’ve been to that fair (it’s every other year) 3 or 4 times now, and it’s quite nice, if the weather is good.
I’m going to be there on the 25th of August (if the weather allows), most likely dressed accordingly.
It’s a bit of a hike from the trainstation to the area of the fair (1.2km), but the parking spots aren’t much closer anyway, especially if you are sleeping a bit longer.
There will be a bit of jousting, but not much IIRC.
Centerpoint of the program are the plays of the historical battle between Ottokar II of Bohemia and Rudolf I of Habsburg.
The live-music is always nice and the mead is quite worth it’s price.
8€ admittance is a bit steep, but I never regretted it, if the weather held.
Dürnkrut is every other year as they alternate with Jedenspeigen (which is about 5km away).
And yeah. Having both Saturday and Sunday be the 25th is witchcraft.
To clarify: I’ll be there on the Saturday that is the 25th.