Are those functioning units with the AC, heater, and fios box? If so, what are you going to do if they need repair?

Hello, yes they are functioning. I want to have window seat on top of the heater with the metal screen on the front and cover the rest with an opening door so I can have access when needed. I just need a nice design to do all that. Thanks

I would be very leary of putting a seat on functioning appliances due to the possibility of them being a fire hazard. My husband is a career firefighter so I've become very aware of fire hazards, and that looks like a potential one to me.

Not an appropriate design choice. They need to remain uncovered for proper function.

I don't know about the air conditioner, which I can't imagine functioning properly when covered, but there are many companies that make decorative radiator covers (in all styles, both metal and wood, and some custom-designed as window seats). Our decorative metal radiator covers are original to our 1920's house, and every house in the neighborhood has similar ones. They are not a fire hazard and do not impair the heating function.

Have a custom radiator cover made and then top off with a cushion.

I googled vintage radiator covers. Look in images and there are some plans that you can download. I would extend the radiator cover/bench to the wall (right facing). As far as the A/C and fios box, I would be careful about the potential fire hazard. So, maybe a nice piece of furniture that blocks the view without being too close? A steamer trunk with cushions for seating, or nice chair and ottoman. Or if you don't mind losing a bit of the window space, an armoire or secretary.