I need at least 7 inches to be happy. I thought I was satisfy with 6 since my 1st reader in 2007 was the PRS-505 and then the Kindle 1 & 2. Since I added the Sony PRS-900 in January, it has become my primary reader (still very portable since it's smaller than my Kindle 2). Now I think the ideal screen size for me is 7 to 8.1 inch screen. With the PRS-950 coming, I will finally get rid of my beloved PRS-505 and make the PRS-900 a back-up for the PRS-950. The Kindle 2 is on a long term loan to my nephew (he had it since March and it does not look like he has any intention of giving it back and I'm not asking for it).