Depends on the route tomtoms given you.
I have only limited knowledge of the IoW and didnt venture as far as Yarmouth, but what i did see was some fantastic scenery (and some quite hilly sections) between The Needles / Freshwater, along the south coast to Ventor and Shanklin..i though that'd be a nice ride, albeit the long way round for you.
Logically the A3054 to Newport would be the most likely route (havnt used that road myself), but Newport itself wasnt very appealing (to look at or ride through)..and quite busy.
From Newport to Brading ?...there some probably quiet B roads, but then i used some of the B roads further north, quite hilly, bendy with lots of blind sections that i didnt think were particually appealing for cycling along either.
Otherwise its the A3056 from Newport to Shanklin / Sandown then up to Brading.
Plenty of hills...probably not an issue for you, coming from Dorset.