My Tuberous Begonias were very nice this season, I am in north eastern Ohio in the middle of a soybean field where the temperatures were regularly in the 90s.
The exposure you gave your begonias was a little harsh, begonias need protection from wind and hot mid day sun. Make sure that the begonias are watered while the sun is not directly on the plants - if they are hot and dry they don't take up water very well when the sun is beating down on them. Tuberous Begonias like to be fed regularly while in growth! My tuberous begonias will continue to grow and flower into October, and then go completely dormant by the end of the month - let your plants go through the end of the season exposed to natural daylength outside which will cause them to become dormant - keep them drier during this process - keep an eye on the weather and don't let the plants go through a hard freeze.
I've included a pic of one of my hanging basket picotee tuberous begonias from this summer - they were and still are beautiful!

You inspired me to take some pictures of my begonias before they finish for the year. The following pic was just taken today, 9/22/12. To answer your question - it was a great year for Tuberous Begonias!