Having an IPS panel 16:10 monitor, I can definitively say that both those features are worth it. Now, if you go for 23in, then immediatly u fall in the 16:9 range, so that would let me an IPS panel to recommend you.
Here are a few suggestions:
Dell U2312HM This monitor is brand new, so there is not much info about it and I have read nothing at all about it. I believe its a "low quality" IPS panel, which means it should beat just about any TN panel.
Dell U2412M This monitor is also new, its basicly the same thing as the above model. Its basicly a lower end version of my monitor. Its an IPS panel, 24in and 16:10 which could still make it quite appealing.