I would specifically avoid combo units. Your receiver will handle the separate inputs and you really want to focus on a decent DVD player with pretty much any VCR out there since it will not look that great on a 20" tv, let alone a 100 inch screen. That aside, if you ever have a problem with a combo unit, then effectively, half of the unit is dead and you either replace the entire thing or you get another unit and end up with a broken piece and a separate piece anyway.
For VCRs, I like the old Mitsubishi HSU-778 model, but apparently that is not made this year, so I am not sure. I would definitely look for something with discrete on/off codes so you can get a good programmable remote or control system to make the room easier for you AND THE REST OF YOUR FAMILY to use.