It all depends on what look you're trying to achieve, and perhaps the size of your bathroom. We have 2 full baths and one 1/2 bath. Prior to our remodel, the smaller of our bathrooms only had tile in the shower, and in our MB, tile in the shower and around the tub (which was separate), about 1' up the walls from the top of the tub. The walls outside the shower were painted. The 1/2 bath had no tile on the walls. (All three had tile floors.)

In our remodel, in the smaller of our bathrooms, along with the floor, we are tiling the wall opposite the vanity to chair rail height, painting above that tile, and tiling the shower. There will not be any tile on the wall where the vanity will go. In the MB we are tiling the floor, the shower, and the walls around the nook where we are putting a freestanding bathtub. We are not tiling the wall with the vanity. In both of these bathrooms we'll be painting the vanity wall. And our 1/2 bath will have tile again only on the floor.

I would tile to whatever a multiple of full tiles + bullnose is:

For example with 4-1/4 square tiles 8 tiles is 34" and a 2" wide bullnose makes 36", but if you use a 4-1/4" with a bullnose you could stop at 34", or the next full unit is 38-1/4".

If you are using subway, it's all going to be multiples of 3" high.