Ticino
Switzerland's small, Italian-speaking region (called "Tessin" in German & French) is south of the Gotthard pass; this region is warmer than the rest of the country, and has food and culture not unlike that of Lombardy south of the Italian border. The Monte Ceneri range splits the region between the north (Sopraceneri) and south (Sottoceneri). Sopraceneri contains the most land, including the capital Bellinzona and 3rd-largest city Locarno (on the shore of Maggiore Lake). Sottoceneri contains a slight majority of the population, including the largest city, Lugano (on the eponymous Lake Lugano).
Roughly from north to south:
Alto Ticino
The northern Sopraceneri (or "Alto Ticino") and valley ("Valli") districts of Blenio, Leventina, Riviera and Vallemaggia are relatively sparsely-populated and feature mountains and valleys, including a bunch of rifugio lodging. Some popular valleys include Valle di Blenio,and Val Bedretto.
Airolo - town at the southern end of the old Gotthard tunnel
Osteria Tremola san Gottardo - rec'd Michelin in 2022
in nearby Bedretto: Locanda Orelli - Michelin Bib Gourmand in 2022
Bellinzona District
Bellinzona is the cantonal capital and home to three UNESCO World Heritage Site castles; it's easy to get to by train from the north or south.
Places to eat in Bellinzona:
Castelgrande - rec'd Michelin in 2022
Locanda Orico - rec'd CN Traveller, 1 Michelin star in 2022
Locarno District
This district extends up into the Alto Ticino, but most of the population is on the north shore of Lago Maggiore, especially in the twin towns of Locarno/Ascona. A bit quieter than Lugano, so if you want a more "relaxing" stay it's a good fit (if you want to be where the action is, go to Lugano).
Ascona - just next to Locarno near the top of Lago Maggiore, this is a really cute, romantic town that many people's favorite in all of Ticino
Aerodromo da Nani - Michelin Bib Gourmand in 2022
Seven - rec'd Michelin guide in 2022
Hide & Seek (in Giardino hotel) - rec'd Michelin guide in 2022 (there's also a more informal "Bar-Lounge" with a somewhat fusion-y menu)
La Brezza - 1 Michelin star in 2022
Locanda Barbarossa - 1 Michelin star in 2022, rec'd Time Out
Ecco (in Giardino hotel) - 2 Michelin stars in 2022
Grotto Ca'Nostra - received a "classic" Best of Swiss Gastro award in 2020
Ristorante Al Lago - received a "classic" Best of Swiss Gastro award in 2014
Ristorante della Carrà - received an "international" Best of Swiss Gastro award in 2015, also rec'd Rough Guide
Al Torchio - rec'd Rough Guide for rustic local specialties
Antico Ristorante Borromeo - rec'd Rough Guide for miss of Swiss & Italian dishes, popular on TA
Elvezia - rec'd Rough Guide for pizza and fish
Mastrolucibello at Caffè Borghetto - rec'd Rough Guide for coffee/pastries/ice cream
Collinetta - popular on TA
?Osteria da Ketty & Tommy - popular on TA & Google, also has rooms for rent...looks nice
Grottino Ticinese - popular on TA, rec'd Time Out
Grotto La Risata - popular on TA
Ristorante Antica Posta - popular on TA
Osteria Ferriroli - rec'd Time Out
Grotto Broggini - rec'd Time Out
Pasticceria Pinotti - rec'd Time Out
Vera Gelateria - rec'd Time Out
Confiserie al Porto - rec'd Time Out
Locarno
Da Valentino - rec'd Michelin in 2022
Locanda Locarnese - rec'd Michelin in 2022
La Rinascente - rec'd Michelin in 2022
in nearby Muralto: Osteria del Centenario - rec'd Michelin in 2022
Towns near Ascona/Locarno
Losone
Centrale - Michelin Bib Gourmand in 2022
Osteria dell'Enoteca - rec'd Michelin in 2022
Ponte Brolla
t3e terre - Michelin Bib Gourmand in 2022
Da Enzo - rec'd Michelin in 2022
Centovalli - rec'd Michelin in 2022
Brissago (towards Italian border):
Osteria Borei - very popular on TA/Google
Ristorante Agorà - very popular on TA/Google
a bit further out in Centovalli/Intragna: Stazione Da Agnese & Adriana - rec'd Michelin in 2022
Lugano District
The eponymous town of Lugano is the most populous town in Ticino, overlooking Lake Lugano
Lugano
Massagno (suburb): Grotta della Salute - Bib Gourmand 2015
Medrisio District
Also called "Mendrisiotto" district, the most southern part of Ticino (and Switzerland) has rolling hills with vineyards (some call it "Switzerland's Tuscany")
Mendrisio
Grotto Loverciano rec'd CN Traveller
in San PIetro di Stabio: Montalbano by Mirko Rainer - rec'd Michelin in 2022
in Chiasso-Seseglio: Vecchia Osteria Seseglio - rec'd Michelin in 2022