Montreal’s oldest Catholic Church, dating to 1656, includes stained glass that chronicles the history of the city. The city’s Parisian-style historic district, with cultural landmarks, boutiques, cafes, and restaurants, can be toured in a horse-drawn carriage for the full vintage effect. La Grande Degustation de Montreal (Nov. 2-3) attracts wine producers, distillers, and brewers from around the world. Montreal also hosts the 24th-annual French Language Film Festival (Nov. 1-11) featuring contemporary films from around the world subtitled in English. When it’s cold, visitors can head to the underground city, a network of tunnels, corridors, and plazas with more than 1,000 retailers and restaurants. The Montreal Tower Observatory, the world’s tallest inclined tower, provides breathtaking views of the city, the Laurentian Mountains, and St. Lawrence River Valley.
My top recommendation would be San Juan, Puerto Rico. It offers a wonderful mix of history and culture and nightlife and great food, alongside excellent beaches and abundant activities. Hotels and rental apartments are mostly in the mid-range for the Caribbean, but food and drinks and most other things are great value. You could get a place in the Condado area, which is close to the lovely Old San Juan neighborhood and plenty of nightlife all around. And then perhaps you could rent a car and stay for a few days at one of the smaller beach towns elsewhere on the island. You wouldn’t even need a passport, although it does feel fairly exotic while you are there. But because it’s part of the US, it’s also well organized and safe. Most people you’ll meet will speak at least some English, and many are fluent, so it’s easy even if you don’t speak Spanish.
The food, including its famous ceviche dishes, is a particular highlight here, and the tourist district of Miraflores is packed with interesting and cheap restaurants. Basic and cheap hotels are in the same neighborhood, so it's a better alternative to the historic center of Lima for most people. By the way, the rainy season in Cusco starts in December, so the trails can sometimes be cut off, although many people go anyway.
If you are looking for something far less developed than Phuket or any other Thai island, Boracay might be for you. This gorgeous strip of sand is a bit out of the way, but partly because of that it still feels only partly discovered. You'll spend your days relaxing along White Beach or walking up and down the sandy paths that serve as the only real form of transport for most people. Many visitors come every year, and quite a few of those never seem to leave.
Like so many others on this list, Goa is completely done with its harsh rainy season by the time November begins, yet crowds don't really start showing up in earnest until mid December. If you have the time off then you'd be very happy just finding a cheap hotel in one of Goa's beach towns and just chilling the whole month in great weather and with minimal crowds.
If you can, try to stay at a hotel or hostel that has a kitchen which guests are allowed to use. You can also elect to find home-share style lodgings, as people often rent out their homes during peak vacation times for tourists to use. Once you have a kitchen, you have control over what you purchase and what you eat. An added benefit of this style of travel, other than the fact that you can stick to your Keto Diet effectively, is that you get to experience the local side of life. Going to grocery stores, choosing from local ingredients, and cooking for yourself will help make you feel like you’re a part of the culture, instead of only a visitor.
You mention New Zealand and of course it’s summer there then, so it would be a good choice. However, all of these places will be crowded and near peak hotel rates if they are warm. So I’ll be happy to give you advice if you tell me if you’d rather visit one or more European cities in the cold season, or if you are looking for a warm place like New Zealand where it will be fairly crowded. By the way, the southern European cities such as Rome and Barcelona are lively and enjoyable that time of year, as the Christmas season goes on, and there aren’t too many tourists except for a few that travel to see their families around the holidays. So it can be a good time for southern Europe, as long as you don’t mind wearing a jacket or jumper during the day, and maybe a bit more in the evening. Give me a bit more guidance and I’ll be happy to try to help. -Roger