"How do architects usually figure this out?"

Architects are intimately involved with the proposed house they designed and the site upon which they are built. They normally have a great talent to visualize, to see things that are not there . . . yet.

I once designed a house on a large hill side a short distance from a lake, but I knew the view of the lake from the house would be blocked by the neighbor's trees. I designed the house to have a least a great view of the trees and maybe catch small glimpses of the lake when the leaves fell off the trees. Low and behold, half way through the construction the neighbor cut down their trees. Now my client has a beautiful view of the lake.

You say the bathroom is framed ... so why not go there, stand in the space and see what your views will be? You should be able to decide the best spot for the skylight.

We spent a ton of time on site and with the plans, photos, satellite pictures, etc. to get an idea of exactly what views we would have from where. Go wander around the site with a camera and get as close as you can, then play with Paint or photoshop and see what you get!

Window views can be predicted with a site plan overlay drawing. Views through a skylight are of less importance but a 3D computer model should work.

virtual reality is able to provide a ”what if”

@chispa The bathroom is framed, but there is a roof over it already, impeding the ability to look through the ceiling.

Unless you are way down in valley, next to a mountain, the ”view” from a skylight is SKY. There is no view. Just glaring sunlight if that roof faces the wrong direction.

This may be an oversimplification, but should work.

Go to the place you’d like to see FROM your bathroom window. A hillside, pond, mountain, or whatever. Look at your new house. Depending how far away you are, you might need binoculars. Can you see the roof of your bathroom from there? That’s your answer.

Hopefully, from the view from the "hillside, pond, mountain, or whatever" you will see a good looking house.

You should be able to tell roughly by standing outside the house and looking at the roof to see what the view will be from a skylight. If it's close to another part of the house with another story or overhanging eaves you may see that if it's Very close.

You should be able to tell roughly what you will see from a window if there is a window on the same side of the house on the same floor, unless the view is very constricted by another building very close.

For a skylight , go on the roof, lay down and look up. That will be the view through a skylight. For a window, do the same thing but stand up (oh, and look in the direction the window will look).

You're welcome...!

@Jillius this will be difficult. The idea of laying on the roof and looking up is missing the point that you want to NOT see the garage roof overhang. Standing where a window will be also is a bit simplistic but an easier call than the roof. Two alternative options are no window, and a tubular skylight that lets in light but has no view. I have no windows in any of my bathrooms and prefer it that way. But sometimes I think about a tubular light for my super dark living room with only north-facing windows. Before installing a skylight of any kind, I asked myself if I would like how it looked on the roof from outside and it was a definite NO. I hope I have been a little helpful.