Your take home message would definitely not be wrong. Though for nature lovers, I'd also add Isola Madre to that message. The manager at our hotel said to make sure we visited Isola Bella and Isola Pescatori. But if running short of time, to catch Stresa as one can give Isola Madre a miss, as there isn't much there.
Well, we saw the magnificent Isola Bella and the okay Isola Pescatori, and decided to pay our 8 Euros and check out Isola Madre. My wife is a bird lover, and she was astounded - hundreds of species of birds either running around or flying around, and some in cages - from Europe, from Africa and from Australia. We took hundreds of photos of them, and then had a tour through the smaller palace on the island. When we got back to the hotel we said to the manager that had we followed his advice, we would have missed out on one of the highlights of our European trip. He seemed puzzled.
The thing about the palaces on the two islands is that they are in sharp contrast to the numerous other Royal palaces we have visited in Europe. Most of them try give the impression of power, or in Vienna of just being very dour. Whereas the two on the islands give the impression that real people lived there - and that they were happy people.
Cheers,
Renato