Maggiore....Locarno/Ascona or Stressa????

Patsy,

I'd suggest staying in Stresa as it's a beautiful city with some interesting attractions such as the Borromeo Islands. While there you could also travel to Domodossola via regular train, and then take the scenic Centovalli Railway to Locarno, returning to Stresa in the evening via boat. Be sure to take your Passports, as you'll be in a different country.

Another vote for the Borromean Islands and the Centovalli Railway. I've done both twice.

We've stayed in Ascona and visited Stressa. I think for a base I'd stay in Stressa for its convienient train and lake excursion options, number of restaurants and longer lake promenade. We stayed in Ascona on the last days of its tourist season and many shops and restaurants (3rd week of October) were closed.

Stresa (actually spelled with one "S") is a better choice for convenience to reach the islands.
Locarno is on the Swiss side, and prices will double as soon as you cross the border.
Besides the islands and the Cento Valli railway, I recommend to visit the village of Cannobio, just before the Swiss border coming from Stresa. Lake Orta, with the beautiful ancient village of Orta San Giulio, is also near.