Oh I think I see where you're going with this..
Budget.. as little as possible but am flexible, whatever it comes out to really.
The receiver has 2 toslink and 1 coax digital input.
The parents get confused with the amount of button presses really, on the TV its kind of a convoluted process to change the input, then they forget which input it is even if I write it down.
Then the receiver itself is a little quirky, it has a DVD and DTV HDMI input, but the DVD audio input is only coax.. whereas theres toslink for "CD" and DTV, since the "DVD player" is the PS3, it was hooked up to the DVD video input and the CD toslink input. DTV was occupied by the set top box (cause its used the most really). Then the HTPC was plugged into the coax input, but I recently rebuilt it and it doesn't have coax anymore.
Not sure why I didn't think of it before, but I suppose I could get a super basic HDMI switch and connect it straight to the TV, the set top box has digital coax so it could use that.. then just get a universal remote to change input on the hdmi switch and the receiver.
However I'm still all ears to a better solution xD