If you are looking for a day trip out of the city, then I highly recommend Boyne Valley Tours. Michael Fox is the owner and he drives an Audi. He will design a route based on the sites that you want to visit in the Boyne Valley. He will get you to Newgrange early in the morning before the tour buses. He also has some great ideas on places to see/visit that may not be on your list. He has lots of great info on places and is very reliable, prompt, and friendly.