What's a good flat screen client monitor?  Medium size and  price range.

Boy!  How long's a piece of string?

Are you talking professional broadcast, industrial, or domestic?  What do you regard as medium size?  What sort of price range are you interested in?

Making your request as open as that makes it very hard to answer.

Also, are you working SD, HD or both?

We're SD-only, and we use a Panasonic CT-L1400 on the client desk. (Pssst: It actually isn't a terrific monitor. Our largely inexperienced clients just like the fact it is a flatscreen, so it must be good!)

You've hit my favorite subject. The complete lack of a decent CRT substitute.

ALL of the LCD panels suck for numerous reasons, but the lack of black and the limited viewing angle are the primary ones for you. They all have a sweet spot dead center, then as you move off axis left or right, or up and down, things change. So it becomes a question of what exactly is the client seeing.

If this is for offline, where no critical color evaluation is being made, then buy the cheapest useable LCD. I like the Dell 2408WFP.

They aren't that expensive, and they have HDMI, SVideo, and composite inputs built in.

We use them on our offline edit systems.

For online, but the Panasonic TH-50PF10UK and get the HD-SDI board to add to it. This will set you back about 3,500 configured that way, and it is 50", but you can mount it up on the wall behind your console and everyone in the room sees the same picture.

They make a consumer version that is cheaper, but you can't add the SDI board and you don't have the full range of adjustments you need to really dial the picture in. 

Don't buy an SDI to HDMI  converter and try using the HDMI input. It doesn't support 23.98 psf.