You mentioned Grand Rapids. Let me first suggest that the best breweries in the area are not in Grand Rapids itself, but within ~1 hour of the city. I say this specifically with Transient and Arclight in mind, though no doubt many would suggest Old Nation or One Well in that same spirit. Of course, Transient and Arclight are in the middle of nowhere; Transient is in Bridgman, whose only other feature is a couple of other breweries (Haymarket and Tapistry), and Watervliet, where you'll find Arclight, has even less going on.
That said, you definitely have plenty of options within Grand Rapids. And the good news is that Transient in particular shows up reliably in the city these days. Better bars frequently have one or more of their beers on tap regularly, and sometimes a few bottles or cans. Better bottle shops will usually have a few things from them, and their hops are some of the only ones that turn over quickly in town, so you can confidently buy anything you see from it.
I can certainly provide bottle shop suggestions or non-beer restaurant suggestions if you'd like, but I'll provide you with the general highlights. I'm going to list only places I believe welcome children through the dinner hour or later, but I don't have any, so it isn't something I've ever paid close attention to, so double checking may be in order.
Breweries:
- Founders Brewing - At any given time there will be upwards of a dozen beers available exclusively at the Grand Rapids (or in some cases Grand Rapids and Detroit) taproom(s), some of which are really fun barrel aged experiments. If you're among those who still care about KBS and CBS, they aren't permanent features at Founders, but they show up significantly more often than in the wild. The food sounds much better than it is, so I'd suggest eating elsewhere first. A word of caution: nights and weekends at Founders are often absurdly busy, even with their massive expansion. If you have the luxury of doing so, mid-day visits during the work week are your best bet.
- Speciation Artisan Ales - Michigan's first all wild ale brewery, Speciation is widely considered to be the best brewery in the state. Their Comstock Park taproom is inconvenient in location, but even more so with respect to its hours of operation. At present, Speciation is usually only open one day a month for bottle sales, during which time there are also a few draft offerings. However, they've been known to open up especially for non-locals who ask nicely, so call in advance if you'll be in town when they're closed and can get there. Note that the taproom is supposed to have regular hours "soon," though nobody is clear on what that actually means. Also note that they are probably the most expensive brewery in town. Expect to pay around $25 per 750 ml for their more interesting/desirable options. And some bottles are restricted to "Culture Club" members, so you'll need to trade to acquire those. On the upside, you can find them almost everywhere in bottles or on tap.
- Brewery Vivant - A Belgian-style-focused brewery built in a former crematorium. Usually a number of taproom exclusive beers available. Food is often excellent, but just as often painfully overpriced (see: Duck Nachos). The poutine is the best in town. A fairly respectable sour program going. Check for special events, as they sometimes host festivals or special events. Most recently they did a "Weird Beer Weekend" which featured a surprisingly good banana curry beer.
- Greyline - One of the city's relatively newer breweries, Their head brewer cut his teeth working at Founders, helping develop recipes for Dirty Bastard, KBS, and Blushing Monk, before going over to Perrin and developing several of their core beers. Their Alpine location is somewhat inconveniently located, but much less so than Speciation.
- Harmony Brewing/Harmony Hall - Two locations, there's the Eastown original and the somewhat larger and much more centrally located downtown Harmony Hall. Their beers are very hit or miss, but there are some gems in their lineup, and their sour program was started by Mitch Ermatinger, owner/brewmaster of Speciation. The original location has by far the best pizza in town. Apparently as of a month or so ago, the downtown location has abandoned its sausage menu and now serves the same pizza.
- Hopcat - Hopcat brews some of their own beer, a number of which are excellent, though just as many of them are terrible. However, Hopcat's focus and its main strength is as a beer bar carrying others. Save for special events elsewhere, they almost always have the best taplist in the city. The food is also pretty good. Note that Hopcat is now a chain, but the Grand Rapids location is the original. Frankly, some of the expansion locations are better, and all of them have more taps than the Grand Rapids location, but it is on the strength of this one venue that Hopcat became a national player.
The other spots I would tend to suggest are places where I've never once seen kids, so even if technically permitted are likely to be poor choices.
We do have minor league baseball, and their stadium is out in Comstock Park, somewhere in the general vicinity of Speciation. The only real locally significant site that one might tend to suggest, though its merits with younger children are dubious at best, would be the Ford Presidential Museum.