What are Enlightenment values?

The RSA is debating a lot at the moment about '21st Century Enlightenment' - about the need to return to and update the ideals of the Enlightenment for our own age. A similar argument has been made recently by Tzvetan Todorov, in his book In Defence of Enlightenment, which came out at the beginning of the year. We should return, Todorov insists, to 'Enlightenment values'.
But what the hell are Enlightenment values? Was there ever a more heterogeneous farrago of moral theories than the Enlightenment?
A cliched response would be that the key Enlightenment value is reason or rationality. But that's not true. Many of the most famous Enlightenment moral theories are based on sentiments and feelings, not rational thinking. Hume famously said that reason should be the slave of the passions. Adam Smith's moral theory is based on the sentiment of approval. Rousseau's moral theory - at least in Emile - is based on all sorts of strange psychological and emotional notions, like amour-soi and amour-propre. Yes, Kant might base his moral theory on 'pure reason', but he's just one voice among many.
Perhaps, then, the key Enlightenment value is autonomy and the freedom of the individual. But that's not true either. One of the main Enlightenment figures is Frederick the Great, the model of the enlightened despot, who employed Voltaire as his private philosopher. How ever could a despot be enlightened, if the Enlightenment's key value is the freedom of the individual?
Think also of Rousseau's Social Contract, surely one of the top ten Enlightenment texts, which suggests that the individual's voice should be completely subsumed in the General Will - a book, in fact, which led fairly directly to Robespierre's Dictatorship of Virtue.
Indeed, some of the most famous Enlightenment thinkers, such as Mettrie, Diderot or Holbach, didn't seem to believe in free will at all: man is a machine, and ideas of freedom and autonomy are merely one more superstition to debunk.
Really, if we had to characterize the values of the Enlightenment, then we'd have to agree with Alasdair MacIntyre that the period is characterized by a complete confusion of different systems, all of them attempting to replace Christianity, and none of them succeeding, partly because none of them satisfactorily answered the question: what is the point of man?