[MMM]

I think some of you are mixing up きれいな（人）and きれいなぁ

The first NA is used when きれい is placed before a noun. The second is a more colloquial phrase, more common in Kansai, but basically has country-wide usage and is used the same way as ね.

So きれいねぇ～　and きれいなぁ～ have the exact same meaning, but different people would use one or the other.