I ferment between 60-64 for a week. As soon as I notice the krausen falling (usually 3-7 days), I take the fermentor out of the swamp cooler and let it warm up to ambient on its own (70-72ish). You room temp might be a wee bit too warm, but I would let it warm up a bit.
Now that you mention it, I have noticed extended yeast rafts. Definitely not krausen, but like clumps of yeast left on top. A few batches they actually hung around until bottling, but the hydrometer said it had been done for two weeks so I just went ahead and racked!