That's exactly what we're doing- I love the grilles, but in the back I didn't want to interrupt the view. We're doing casements for the all-glass look. I put grilles on the windows in the front of the house, but not the sides or back. That way it looks uniform from each elevation. I don't have any rooms that had both a front and side or back window, so I didn't have to figure out how to work wight that scenario. Good luck!

while I'm more concerned with efficiency of windows
(solar heat gain coefficients & ufactors),
my personal prefrence is no grids in windows.

it is purely a personal choice, what pleases you?
it is your house/window/view.

best of luck.

We have full muntins on our front windows and have them only at the top on our rear windows, except for the large DR window which is open to the library in the front, so those windows had to match.

You can certainly do grillwork windows on the front side and plain on the back. I see it all the time.

But if your home is designed to take maximum advantage of natural light, then you WILL have rooms with windows facing in two directions....quite possibly in every corner of the house... and that means those rooms are likely to have windows with grills on one wall and plain windows on another which I personally think would look really odd.

In my house, every major room has windows looking out in at least two directions and the great room has views in three directions...plus, from the great room, you can see thru to the breakfast nook where there are windows looking out in the fourth direction! Thus, there was no way that I could do grills on windows facing one direction and leave them off on windows facing another direction and have any consistency from within the rooms.

What I did instead was to have grills (the window companies call them SDLs for "simulated divided lites") installed on the upper halves of my double hung windows while leaving the lower halves plain. Most of the time when looking out at a view, I find that we're actually looking through the lower half of a double hung window anyway. I also chose the 9-lite "prairie style" pattern for of grills which, particularly on larger windows, also give you with a fairly large unbroken span of glass in the center of the upper window also.

I think the 9 (praire lite) over 1 pattern gives me the best of both worlds... good views from inside and some window texture for the exterior look. I also used the 9 lite prairie style pattern in my patio doors and in a couple of half lite doors that lead out to upstairs decks.