Travel between Zagreb and Ljubljana

We took a train from Zagreb to Ljubljana. It was a pretty ride and was just under 2.5 hours. It was really easy, but keep in mind we like to walk...you don't give the age of your child, so the walking parts might be a little harder. At any rate, we stayed right near the main square in Zagreb and walked to the train station in less than 20 minutes. You could take a cab in 5. Once we arrived in Ljubljana, we again walked into town from the train station - 20 minutes tops. I wouldn't suggest flying for this leg of your trip.

Consider using the shuttle service Go Opti for travel between the two cities. It's rather inexpensive and takes about 2-3 hours. In Ljubljana, make a day trip to Lake Bled. I wouldn't suggest flying out of Ljubljana. Airport taxes are extremely high.

There are several direct trains a day between cities, and that's surely how I'd do it (I took a train several years ago from Ljubljana to Zagreb). Ljubljana's core is small and very walkable, and I walked to my lodgings when I visited. There are also local buses if need be. Zagreb is a little bigger than Ljubljana, but there are trams that take you from the train station into town; I took a tram from the train station to my hotel in Zagreb.

I don't know what difference the order of visiting cities would make. I'd probably base the order on scheduling my flights into/out of Europe or other logistics.

The Zagreb-Ljubljana train is simple and only costs perhaps $15 per person to buy tickets there in 2nd class, or 50% more in 1st class. In that direction, the direct trains (no connections) run in the afternoon, e.g., departing Zagreb at 12:30 and arriving Ljubljana at 15:00. In the other direction, there is a direct train at 8:25 a.m. or 14:45. As others said, the centrally-located train stations are fairly handy to hotels. (Train schedules also reflect one direct bus per day.) From Ljubljana to Lake Bled, for instance, buses run frequently and the bus station is near the train station.

Thanks to all for your help with this topic. I was also thinking either Go Opti or train, so you have confirmed my initial thoughts. Our son is 6y so we would be taking tram or taxi from train station to the hotel. For the train, would it be ok if we bought the tickets a day in advance?

GoOpti was great for our family. I would definitely travel with them again.