Im wondering if we should install a pannel of sliding glass doors on the right or just two windows and have the tv in the middle?

If you think you will add a deck or patio later you should be planning some way to access it. You don't want to be altering the wall later to do it. But the TV would look good between two windows. Some people like symmetry. You could always do a floor to ceiling window on one side (or window that stops a couple inches above the floor) and an operable glass door on the other side.

If we did a large sliding door to access a future deck, how would we design/put the t?

Tv*

With a slider the TV would have to be next to the door I guess. Can you post a drawing on graph paper with both of your options? I don't know how long that wall is or how big a TV you want.