Day trip from Dubrovnik to Montenegro

I have just booked a tour to montenegro.
There are usually 2 tours going to montenegro.
The normal one that run every day includes 4 places. Perast, our lady of the rocks ( optional :additional 5 eur for the boatman) kotor， budva， Sveti Stefan.
Comments of trip advisors stated that insufficient time in kotor but too much time in budva.
So I choose the one that operates on sunday tuesday and thursday. That includes only perast and kotor to ensure we can climb up the kotor city walls.

Maybe you can think of hiring a private tour that serves your family with my schedule only kotor and perast. From previous Rick Steves forum, a member recommended a company called Dubrovnik Cheap Tours, they run private tours with a reasonable price. The comments in Trip Advisor are good. The price is nearly half of that in viator.
Your may check it out yourself.

We did that tour. It's probably too much for little kids. All day. Lot of time going in the van. They have also 2 and 3 day tour to Albania which I would have rather done but did not have time. Montenegro is included.

There are public buses from Dubrovnik to Kotor. They would give you a bit more flexibility than an all-day tour. But with two young children, I'm not sure it makes a lot of sense to leave one walled city to visit another. (And I spent 4 nights in Kotor.) The ride itself, along the edge of the Bay of Kotor, is really lovely. But thinking back to my own childhood, I wasn't much of a scenery fan.

Here's the schedule to Kotor for a randomly-selected weekday in June. The buses are comfortable. You can check for your actual travel date and also look for return buses. It's always essential to double-check bus schedules once your feet are on the ground. And be aware that--even more than for trains--day of week is critical. Also be sure you are aware of any impending holidays. When dealing with buses across borders, it's always advisable to buy the tickets ahead of time. Sell-outs are possible. I don't mean that you necessarily need to buy tickets over the internet before you leave home.