Personally I think it will look odd if these headers are not over every window and 13" seems quite tall for your realatively small windows.

What do the elevations show?

Decorative features over windows are essential for replicating traditional designs and can add curb appeal to transitional style homes like yours. Our rule of thumb is to apply the same feature over every window on the front facade of a home as millworkman suggests. Unfortunately, the majority of your windows are jammed up against the frieze and can't accommodate any such feature. The ones that can are mainly on the garage.

A pre-cast masonry lintel will contrast with the brick, and I believe, will detract from the overall appearance of your home. Instead, I would recommend either a 4-course cut brick jack arch or a soldier course of brick above the windows. Use the same brick--not a contrasting brick.

As with any architectural detail, it is best to have your architect/designer show it on the elevation so you can make an informed choice between the available alternatives.

Our house was designed with the intent of headers above the highlighted windows and the remainder of the windows tight against the frieze board.

I do agree that 13" seems large.

I assume you will be using cast stone. What will the color be of it and the brick. You should always design using a drawing showing all the visual considerations.

The lintel height must be sized to fit in the brickwork. A lintel height of 3 brick courses is common. IMO 2 brick courses would be the smallest and 4 brick courses would be the largest.

Assuming one less mortar joint than the number of brick courses and a 3/8" mortar joint, the lintel height dimension choices would be would be 5 7/8" (2 bricks courses tall), 9" (3 brick courses tall) and 12 1/8" (4 brick courses tall)

Check my math and adjust for a different joint size or bedding detail if appropriate.

I recommend the 9" lintel.

A 13" lintel would require very large mortar joints.

Will you have a precast sill?

It will look odd if other windows, with the same conditions as the windows with lintels, do not have lintels; and that goes for all sides of the house. I hope you do not have a Hollywood set house that only has brick on the front.

I think a precast sill may look good.

Thanks for the input. The whole house will be brick and the other windows on the back and side that have the same situation will be treated the same.