Windows are sized differently by different manufacturers so I have assumed the sizes you specify are frame/unit sizes.

The numbers you mentioned do not add up to the ceiling heights so you might need to review and correct them.

For instance on the first floor 18 + 60 + 18 = 96 which is a 8 ft ceiling ht. instead of 9 ft.

At the rear first floor 12 + 60 + 12 transom + 12 = 96 which is 8 ft instead of 9 ft.

Interior stool heights of 12" and 18" make rooms difficult to furnish unless they are very large and it increases the cost of the windows for tempered glass in the lower sash.

I can't comment on inaccurate dimensions but I would suggest you make the windows wider than a 30" frame size unless you are trying to make them look like historic colonial windows which IMO are really too narrow for modern houses. And if you want them to look authentic, the shutters should be 1/2 the width of the windows instead of 1/3 as drawn. The panes should be taller unless you really want the them to be about 7 1/2 x 8. That would make sense if the panes were 4 over 4 in a larger window.

Putting brick up to the height of the garage window sills is an architectural joke for a traditional colonial house. In a traditional house cladding material should change at floor lines as if they were real rather than simulated.

Sorry i thought those window dimensions were standard language but to clarify by 3060 i meant 3 feet wide by 6 feet tall - not 30 inches by 60 inches. We do want the shutters to be 18 inch wide so they will be half width, which is something that needs to be corrected on the plans so thank you for pointing out. Not sure we have an option on pane size as none of the brands we looked into asked for our specs for grid size but something for me to look into. And we like the look of brick/siding combo on the garage, which I know may be appalling to some, but luckily we are the ones who will live in our dream home. Any rules of thumb to consider for dormer window size?

Are you using the third floor as living space, or is it more decorative? The dormers look a little large to me, but I'm no expert. The smaller window, over the garage (?) looks like a better size.

Of course, if you need the light on the third floor for bedrooms or play area, then the larger dormers make more sense. Best of luck on your new home! :)