I actually rather enjoy the Glacier course - it's actually a links course. Much more fun to play it when the grass is high and the wind is blowing hard, then it truly acts as a links course. But if the wind isn't blowing, then it's basically a wide-open course. The trick is hitting it when conditions are right. But I wouldn't ever advise a out of towner to visit it.
I've actually never played Flat Rocks. Nor Marysville, or Pickerington but I've only played about 2 or 3 rounds in the past 1.5 years, due to a number of factors. The last courses I remember really rather enjoying playing were Gordon Holton and the Sunbury course.
Keeping in mind your location, and the amount of driving you may or may not mind doing, you may be well served to focus on either courses you can hit in a specific direction, or on just a couple of courses somewhat close to each other. Marysville is relatively close to Dublin, and if you drive all the way out to Sunbury, you might as well hit Glacier on the way back.
Honestly, there isn't really a "must-play" course on the level of Idlewild or Renny Gold around here, but several solid courses that cater to different tastes. If you like links - Glacier, if you like a mix of things - Gordon Holton, and if you like paying $5 to park and playing a round with just your putter and dodging tons of people streaming to/from baseball fields, then by all means, go to the Ohio State course! Hambrick is totally worth a play when the baskets are in, but if even just a couple are pulled, it's not as much fun.