In 50 years of civil jet aviation there has only ever been one case of premeditated ditching - a DC9 in the Carribbean when the Capt suffered a humungous brain-fart and avoided several chances at a landing on terra-firma. Despite inclement weather half the pax survived, most of those who died due to a slide that inflated in the fwd cabin instead of outside thus blocking an exit.
Remember that he crew of the Ethiopian dithching were apparently being attacked with an axe at the time of their - under the circumstances - incredibly well controlled landing.
Remember also the B 707 that ditched in (Lake Victoria?) Africa last year. Crew allegedly mis-set altimeter and struck the oggin at "500 feet" fully configured for a (ground) landing and without flare. The old bus not only preserved the lives of the sinners who had so ignominiously brought about her end, but had the dignity to remain afloat until daylight whereupon the local fishermen hauled her to the beach and, bless them, claimed salvage. I hope, though without much expectation (knowing Africa) that they got their just rewards.
The story on ditching remains the same... 999 out of 1000 ditchings are without warning - time to shout, "Brace Brace Brace" to the cabin as you run off / out of runway and SPLOSH! Not much choice or time for anyone.