I love that boat tour of pictured rocks Red, I've done it twice in the past 5 years. It's worth the money. My experience with both rides is that they do a loop, and the way out is slower/longer than the way back. This matters in terms of which side of the boat to get a seat on. And there will be a line to get good seats. And it will be cold on the boat if you sit outside which obvs you want to do.... right? Also be aware the boats can and do cancel a lot because of lake conditions. We had one of our rides cancelled because of 6-7 ft waves.
Munising is unexpectedly cold as bleep. I took a long phone call on the lakeshore where the tour boats are last July and I had on a Sweatshirt and winter coat.... in july.
The UP is amazing but really spread out and sadly a lot of the other sweet stuff is a ways away from Munising. There are a number of waterfalls around Munising and going to the lookout points above Pictured Rocks is pretty awesome too. Lots hiking available. Could probably spend .5 days or so in downtown Munising, there are some neat shops there esp for outdoorsy Patagonia types.
Disregarding distance, things to check out in UP if you can:
Soo Locks is nerd neat but kids will be bored. Can be uneventful if no boats but also very very slow when there is a boat lol. Bear farm place near Tfalls is really expensive and imo not worth it. Also probably not the most humane thing for the bears. Kipikichee (may have spelled that poorly) is pretty neat but maybe a bit overrated.
Upper Taq Falls is beautiful, lower Taq Falls is super fun because you can get in the water.
Bond Falls is really cool too but quite far away from Munising. Porcupine Mtns was super nice I thought.
There's a brand of Wisconsin ice cream that alot of stores carry up there that is super delicious and you need to get some of that, I apologize I forget the name but you'll see it at all the places that sell ice cream cones.