I previously played a science victory in Gods & Kings, with Korea. The end of that game went sufficiently awry that I wanted another shot at cracking the 200 turn mark for a science victory.
For the civ I took Rome. Largely because I always wanted to play Rome but hadn't yet. The unique ability looks pretty strong, +25% production for any building that already exists in the capital. Rome isn't known as a science civ, but I think this will actually work out fairly well. The Korea game showed me how maximum velocity for science gets stuck in the chunkiness of endgame bulbing, so the highest beaker velocity might not actually be what you need, unlike Civ 4. I think it's more important to ramp up faster and start bulbing sooner even if terminal velocity isn't quite so high. And obviously Rome is a master at developing cities quicker.
And no matter what, Inland Sea is always the right way to go. Most chunky desert, most rivers, most ancient ruins, easy to find all the city states, few fronts to get attacked. BTW, desert is determined only by temperature (Hot). Rainfall controls jungles and forests, but not desert. So make it wet.
This report is my second attempt. The previous try had left me unsatisfied by the midgame after the pantheon came too late and my religion spread too slowly. There is a serious difference between Desert Folklore on turn 20 versus turn 40, and between religion on turn 40 vs turn 60. Missionaries need to start early early early, while there still exist size 1 and 2 cities that will quickly convert for free and multiply the overlapping pressure. That 20 turn margin means a difference of several missionaries and ten or more cities converted, and obviously ten happy via Ceremonial Burial is huge. In that aborted attempt, each of my neighbors had already founded their own religion by the time I got missionaries going, and I was awkwardly placed in a corner of the map with no other neighbors within pressure or missionary range.
That attempt also went Liberty, with which I became seriously dissatisfied compared to Tradition. Enough so that I had to write up a full article giving that the analytical treatment.
Desert Folklore ahoy. Alea iacta est.