The thing with Hopcat is that they have a TON of taps, with lots of great Michigan and regional beers (and some world beers), and the place is very nice. I had the Killer Mac and Cheese and couldn't say anything bad about the experience... Except the beer.
They do brew their own beer, but this spring when we went, the Kolsch was off. The manager admitted it, and I imagine it was because they were still learning the brewery system. Plus they advertised a DIPA, but it wasn't available. Apparently it was for a charity event, and I think they were planning on selling the leftovers or something.
Hopefully they have figured out the brewing system and are now making some decent beers.
However, Founders has some of the best beer I've ever had. I like the place and the food as well. I think that is a must-see.
I've been wanting to get to Arcadia for a while now. Not just because I think the beer is good, but I've been wanting a tulip glass with the sword logo on it.
I have not been in Bell's bar, but it doesn't sound like my kind of place. I have been to the LHBS there though, and can't complain about that too much. I like most of Bell's beer, but not all of their beer suits me personally.
I have not been to New Holland, but enjoy their beer as well. Another place to add to my road trip list.
If you are going north, Mountain Town Station houses Mount Pleasant Brewing Company, and although the beer is just OK IMO, the food is pretty good and the restaurant is housed inside a working railway station (Last time we went the train arrived and people walk right off the train and into the restaurant/bar area, right next to the bar.
Further north I recommend Right Brain. Cool atmosphere and usually some very unusual and usually very tasty beers. They are always changing the beers around, but the brewmaster knows his stuff and keeps it all delicious while interesting at the same time.
Michigan Brewing Company is pretty good. I prefer the Celis White to any other Belgian Wit. They also have a decent LHBS on-site. Can't really go wrong there.
East of that I can be no help. I can say that I've had some Atwater beers from the store and have not found a good one yet. I'm talking gushers, and beers with weird flavors and strange mouthfeel. Not in a good way either.