The first few portables I built used a KYV-N2 V6 board with a ZJ050NA-08C screen. It's a 5 inch screen, 4:3 at 640x480 and takes 9v-16v DC in according to the datasheets. I don't know if it supports RGB over VGA, so a GCVideo might not work with it, but the composite in works great if you use shielded wire.
Besides that, most any Dalian Good Display is good, they're kind of a standard now and apparently most support GCVideo input too.