The last time I was in Haarlem I stayed at the Hotel Lion d'Or. It's the oldest surviving city hotel in Haarlem, going back to its beginnings as a public house in 1839. http://www.hotelliondor.nl/EN/indexEN.html
It's right on the transportation square with the train station and a small bus center. The bus I took from and back to the airport, #300, stopped there. The cost was €6,50. That was in the summer of 2019. The price is no doubt more now.
I travel solo and was 73 at the time. I was very comfortable there. They had a nice little cafe where I had breakfast and one other meal. I'm not a big foodie, but the food was very fresh and tasty.
I don't know if it was central or not, but I walked everywhere. I think I was there 3 nights before flying on to Lisbon for the RS Portugal tour. As usual, my favorite thing was just wandering around, but I did make a point of going to the Teylers Museum, the Grote Kerk (Great Church) or St. Bavós and the Frans Hals Museum. I'd been to the last before and enjoyed going back again.
Teylers Museum is unique for at least 3 reasons: open since 1784, it's the oldest museum in the Netherlands, it has a widely varied collection and it tries to use daylight as much as possible instead of electric light, making the experience more like it originally was.
I lucked into a noon organ concert at St. Bavós. Its organ was built from 1735-1738. It has 5068 pipes and is almost 30 meters high. Mozart played it in 1766 when he was 10 years old. Händel also played it. I can't imagine how thrilling it would be for anyone to play it. The concert lasted a little over 30 minutes. I sat for most of the time, and walked around part of the time. The acoustics were so amazing that the music sounded equally good from anywhere I stood.
One other highlight of that particular visit to Haarlem was a large and beautiful cheese shop. The shop was beautiful and so were the cheeses in it. On a previous visit to Haarlem, I went to Corrie ten Boom's House/Museum. That's also a worthwhile visit.
Assuming none of these are featured on your tour, I'd prioritize them this way, but your interests and time available might vary: Frans Hals Museum, Grote Kerk, Cheese shop ;-), Corrie ten Boom house, Teylers Museum.