I hope someone on your tour sees your post! My experience is that most tour members are unaware of the forums but maybe someone is lurking!
I did this tour in 2014 and loved, loved, loved it! I did not allow enough time in Haarlem, there is SO much to see there. I'm sure you will enjoy your extra time there and you will be so glad you've given yourself an extra day to get over jet lag. You start out with a bang in Amsterdam which was one of our longest walking days. Really, I think everyone was glad for the bus ride to Bacharach the next day, lol. Be ready for slightly bizarre interior decorating of the rooms at the Ambassador, hahaha! Now, see? You'll crack up when you walk into your room now.
I do have a suggestion for you to consider. I posted advice to someone earlier today when she was asking about suitcase size for the Best of Italy tour but it applies to this wonderful tour as well. If you don't mind, I'll just copy and cross-post here as you'll also be going in to Venice and Monterosso.
"Venice - you'll get off the bus in the bus parking lot and take the vaporetto (might be crowded) in to a dock near your Venice hotel. You'll doubtless have to cross some bridges as you walk to the hotel and the bridges have steps not ramps so you have to lift luggage up and over each time.
Monterosso - the bus can't drive there so you'll be dropped off in Levanto and take the train to Monterosso. You'll have to manage your case up/down flights of steps in both train stations and off/on a train (might be crowded as well) then on to your hotel. On one tour (Heart of Italy) the hotel provided a luggage transfer service from Levanto. On the next tour (21 Best of Europe) we managed our own.
SO, no matter what size luggage you take, for both of these stops I suggest you decant the things you'll need for 2 nights into a small tote/day pack that will be easier to manage. I do better with this if I plan ahead and know what I'm going to take for the 2 nights in each place. I put my clothes in one of my packing cubes and just take minimal toiletries. I generally wear my shirt/pants for several days, so I'd start out with clean clothes on your transit days to both places then maybe just 1 clean shirt and unders for your time in either place.
On RS tours I travel with a daypack or a tote bag for my bus bag. I have my rain jacket, guide book, kindle/iPad mini, chargers, snacks, water, etc and just leave it on the bus when we have a bus day. I use this bag for my overnight bag on either of these locations and have my usual crossbody purse as well"
Have a terrific time on this excellent tour!