I've learned this lesson the hard way too may times. And continue to learn it all the time. Maybe I should write it down...

You'll probably still want a back splash, or at least something water resistant/proof like tile behind the sink. Otherwise you'll get mold or minor water damage behind the sink.

Before we re-did our upstairs bathroom, the counter was two 4 foot pieces that were glued together with wood glue. They did a good enough job that you could barely tell. Also made it easier to get out. Probably depends on how nice the rest of the kitchen is and what material the countertop is.