I love the plantation shutters, too. I have great natural light in my house, its one of the features I loved most when I first saw it. I wanted to keep as much of that as possible. I put shutters on every window where they're not totally impractical... Upstairs almost all my windows are protected from view by very tall trees but I still have great light so I have white plantation shutters on the lower half of the windows up there and on most of them just a bit of fabric above the window or a roman shade taht I have keep pulled up most of the time.
I had the Plantation shutters down the beach.. and I loved the look of them inside and out. I do think I'll stick to those on the front. It won't matter either because there are no other windows in those rooms to contend with.
I will only do half way too, as those windows are facing east, so it should be ok. If not, like you said some sheers or pull-ups of some kind.
The sliders meet in the middle on the lanai and open in a corner, so I might not have any choice on the verticals. Need to keep out the west sun but have something that opens up completely back to both room walls. I hate the damned things, but I think I might be stuck with them.