I have mine set to:

On Battery: Neither WiFi nor remote ever
turn off, backlight 1 minute
On Cradle: Wifi never & Nevo off after 30
minutes

I have been moderately annoyed by the waking/re-establishing
of WiFi, but with these settings that's not an
issue at all....ever. On the flip side, with
these settings I worried about battery life.
However after 2-3 hours of watching TiVo & intermittently
toying around with the Nevo, I couldn't tell one
ounce of energy had fallen off my battery indicator
(hope its accurate).