We have the full Nomex/GoreTex suits, and I wear them when the crossing is longer than about 30 minutes. I figure that the actual 'out of glide to land' time is pretty short.
Wear your life jacket, and have your beacon on your person whatever - that way if you get out of the plane you'll have the minimum with you. Additionally getting the raft out is nice, but less easy.
As far as floating planes goes, my theory is that the less fuel you have, the longer you'll float (thanks to the fuel tanks being full of air). Of course, you need to get the machine down relatively intact.
Taking the S out of SAR is important as well (radio calls and position transmitting beacons etc.).
Fly safe, Sam.
PS lost a colleague a long time ago who dived back into a ditched aircraft to try and rescue someone, and didn't come back up - so be careful if you find yourself in a similar situation.