Background: Family of 5 (kids are 15, 13 and 10) and we enjoy foreign travel and can do it in June/July when kids are out of school. Kids have been to around 10 countries to date, (like Australia, Croatia, Italy, Costa Rica, Spain, Portugal, a few days in France, and some others in Europe etc) I'm posting this as we are in the last few days of our 2019 vacation and we're starting to gather ideas for June/July of 2020 If we plan early enough we can fly about anywhere at no/low fees since I have a lot of airline miles, and we tend to do the budget AirBNB type vacations. So since I want to book way in advance in order to use the airline miles for 5 people its time to look forward and I'd be looking at a time period of maybe 21-28 days in June/July next year. (I can work remotely if I have good internet so going for an extended period of time is the objective)

So ideally here are the criteria and I'd love to get your ideas since there are some major travelers here on the board:

1. Close to water - ocean or lake
2. Good weather in June/July
3. Good train/bus system so we could avoid having a rental car the whole time.....but it would be sweet if we could do day trips to cool places or weekend trips to another country
4. Not overly expensive (so something like Switzerland wouldnt be real attractive)

Suggestions? Is there anything like that anywhere in South America - where neither my wife, nor I have ever been? Lisbon / Portugal would be an option but we're there now (loving it) but returning next year isnt attractive. Unfortunately I dont speak any foreign languages but we've managed to get by ok everywhere so far. Would appreciate any ideas, right now we're in the idea gathering mode.....TIA