DH is going to Northern Croatia with work in May which coincides with a long weekend of inset + bank holiday for the kids. Thinking of taking them out for four days to join him - he'll be in a small town so would probably go for Trieste, Ljubljana or Zagreb, all of which are in striking distance and have direct flights. The kids are boys aged 6 and 3. Any hive mind ideas on which of these would be best with kids this age (or alternative destinations, but nothing too remote as I'll be bringing them on my own!) really appreciated!