Sounds good. We've been a few times a few years ago as it's only a cheap flight away from London. We stayed in various places round Puerto Pollensa and have ridden the east and north-east side of the island. We still have photos of big grins as we rode through gnarled olives up and downhill.
Basically the northern third of the island is mountainous while the middle and south offers rolling / flats. I think the tour will be missing the highlights if it fails to ride to the lighthouse at Formentor and also up and over the mountains down to Soller, which is an awesome descent then climb back up. On a tandem I would want very useful brakes for this. Also the climb to Puig Major is supposed to be nice, but quite hard.
We also did a nice ride down to Cuevas d'Arta on the south of the island and were caught on the way by a local pro and his buddies out on a rest day ride. You could tell he was definitely a pro as he was wearing a long sleeved top and legwarmers at 32 degrees C! We thought he looked quite classy until he told us he was a time trial specialist and had beat Chris Boardman into 4th place in a prologue at the Giro.
The other crazy thing about the island is that it's known by the Germans as the equivalent of the 53rd state. In some places imagine a hotter and less organised version of Germany, complete with Currywurst and great beers. Germans much like English people, only better behaved. We liked it, others don't.
However I slightly disagree on the traffic. When we were there at Easter there were still a large number of dead from the neck-up tourists dawdling in hire cars and crazy locals doing their best impression of WRC tarmac stages on roads that go anywhere. Also some of the mountain roads are narrow and the only way to get from A to B. However once onto the minor roads it's lovely.
Want to go back, but am going to Riccione (Adriatic coast of Italy) tomorrow for a week's cycling, so very happy.