I wanted to avoid the large bus tours when exploring the Boyne Valley, and rather than rent a car and try to navigate all of the locations myself, I opted for a day trip with Michael Fox from Boyne Valley Tours. He was very responsive to all e-mails that I sent, and when he picked me up from the hotel in the morning, he was extremely punctual. The car was extremely clean and comfortable, and it made travel times between sites go by quickly and smoothly.
Michael was extremely accommodating, and he worked with my itinerary in order to see all of the sites on my list in the most appropriate order based upon location and opening times. Newgrange and Knowth were the first stop of the day, and he arrived to the site in time for the first tour of the day to avoid the crowds and ensure a ticket. If you plan on seeing a lot of sites throughout Ireland during your visit, I highly recommend purchasing a Heritage Card for 25 euros that allows you entry into many state-managed sites, including many places within the Boyne Valley.
While Michael is not a trained historian, he does have a passion for his local history that is quite evident. He is moderately knowledgeable about all of the sites within the Boyne Valley, and he knows many of the people at these sites, so you may get an impromptu tour/access by an employee if you are lucky (e.g. at Old Mellifont Abbey I was granted access to a locked chapter house and heard a very interesting story about the property by a guide).
Michael spent the entire day showing me around the area, and I was able to see every location on my desired itinerary, as well as a few added bonuses. This was an excellent way to tour the region and have full control over the sites you visited, without the busloads of crowds that you would expect on a large bus tour. While the tour is a tad expensive for a solo traveler, it is well worth it if you have a real interest in exploring the Boyne Valley and hearing about the history of the region. I highly recommend Michael Fox's day trip!