Are you saying there"s a header above the rod pocket? What size are the valances? Generally they are 12-15" deep. Do your windows crank in? That will compromise the lay of the valances and you'll want to hang them high enough not to interfere with the open windows. If they crank out, don't worry about it. It would help if we could see the window and the valance.

Use some painter's tape and tape up a newspaper "valance" to see what level you like. It may be too much if they come to the bottom of the top pane, so try it covering 1/2 of the top pane. Also try it covering only the top frame of the window. Looks like you have some nice plantation shutters there. Are you sure valances are a better option? If you need fabric and pattern in the room, there are other ways to do that, especially since you sew.

If you're sewing in both a header and rod pocket, try it both ways and see which looks better to you. Do this before you hang the rods. Thread the valance on the rod and have someone hold it up so you can see it both ways. Personally, I like headers because I like the ruffle effect you can get that way. Since your valance sounds tailored and masculine you probably won't have excess fabric to gather up, so you may decide to opt out of the header and just do a rod pocket.