Getting to Keukenhof from Amsterdam is not straightforward, and the crowds are ubiquitous. So anything that can make a day trip to Keukenhof easier is worth it.
Luckily, Gavin, the driver for the day, made this a very easy, stress-free experience on the day. He arrived early at my hotel, and was polite and attentive for the entire trip. His English is perfect, so there were no communication issues. The car was extremely comfortable, his driving skills were excellent, and he provided both water and wi-fi during the ride. When we arrived at Keukenhof, he got me straight in to the gardens, and also came in with me to help me get my bearings and to point out some of the key locations within the gardens, before leaving me to wander on my own as I wished.
However, if you want to visit Keukenhof, I would recommend that, if possible, you not visit on the last day, as my schedule forced me to do. While the experience was still worthwhile, the gardens lost some of their full wow factor because many of the tulips had either died or were just about to do so.