It does no good to cruise on max fuel if you still end up ditching.
The best thing you can do is climb (not to the moon, mind you).
Why?
Because when you DO run out of gas then you can glide for a long distance, banking on that air cushion you built up underneath you.
Scenario 1: You stay low, cruise, eng dies 1 mile from the runway and you ditch.
Scenario 2: You climb, use more gas, eng dies 1 miles from runway, but you can glide her in and dead-stick the landing for a safe return.
You always want some alt under you, even if low on gas. Coming from a guy that makes tons of deadstick (no oil, shot out gas, damaged, etc) landings, it's a life-saver, virtually speaking.