Final Fantasy IX.

I'd want most of it to be close to the original; maybe more polys and higher texture resolution for the character models, better draw distances in the overworld, etc. Keep the pre-rendered backgrounds but have them be high-quality looping video streams with a lot of activity going on. Maybe add some voice work.

But of course I wouldn't trust SE to make this without messing it up entirely and turning Zidane into a skimpily-dressed androgynous J-pop wannabe.