This is a tough one and I'm not sure there's a perfect answer yet. It's definitely come through the board a few times.
We have the Summer Infant deal that has a little handheld touchscreen and can have up to 4 cameras that it cycles through. You can use the intercom on it to talk to the kids, and it has video out. For a long time I used the video out to a dedicated 22" TV in the bedroom so I could see it at night - and had it cycle through the cameras. It's decent, but not perfect... though it definitely gets the job done. We even take it with us on vacation to hotel rooms, and have used the battery pack camera accessory a couple times to watch the kids when they were in a different room. I also played around a little with hooking it to a Grandstream IP Video Encoder to access the video via iPhones/iPads and it was kinda cool. Now admittedly I just don't care that much and don't really watch the thing much but my wife watches it a little too much. I don't like that it has to cycle camera by camera, so getting to 3-4 cameras would take too long. I want something that'll view 4 cameras at once.
I think if I were to do it again, I'd probably wire in a Grandstream bullet camera into each bedroom and power it off an IP POE Switch. At the two TV's, I'd put the Grandstream Video Decoder that can display at least 4 cameras at once and decode directly to the TV so no dedicated computer is needed. You can also use IP Cam software on any handheld/tablet/smartphone. To bridge the Intercom gap, I'd put a handful of wireless SIP extensions around the house (again, grandstream has a system with 4 phones to a base) and use the SIP extension feature of the cameras so that if I need to talk to the kids, I could just "dial" their camera and talk to them. This would again also work via iPhone.
I think this is still what I'll end up doing, although as my kids get older I'm caring less and less; I know when the baby cries, and my oldest (almost 5) abuses the camera to ask for things or keep us up; the almost 3 yr old has nothing in his room and is fine; we also have the Elk which helps keep them safe by alerting me if the doors open during "bed time" so I get a little advance warning before I hear footsteps down the hall, or so I know to keep an eye out if they're just using their bathroom.
As my kids get older, what I really want is a form of tablet on the wall that's a video intercom so I can check on them if needed, and I can call them down for dinner or out of timeout - but start giving them more personal space.
