Best video monitor with the longest range?

I loved our Motorola monitor with two cameras that I could toggle to watch both DC but unfortunately it's dying. The camera in DD's room went out and won't work anymore and DS's is going on and off which is what DD's did before it died. The other problem is that the range isn't great and doesn't reach the other side of our house. We put a drop cam in DD's room but it isn't great. It stops working and the audio isn't great but I do like being able to watch on my phone so range isn't an issue. We are almost done with renovations and the master bedroom will be pretty far from their rooms so we wouldn't be able to hear them without a monitor. Both can need monitoring at bedtime to make sure they go to sleep so we need a new video monitor. Any recommendations? Thanks!

My house isn't huge so I can't speak much to range, but I recently bought a video camera for the first time ever and I've been really happy with it. It's this one: http://www.amazon.com/Infant-Optics-...=video+monitor it's simple but has worked well for us so far. I only have one camera with it though so I can't speak to how it works with multiple cameras.