There are many, many parks in Cincinnati with covered picnic areas perfect for an outdoor celebration. My favorites include Mt. Storm Park in Clifton and Ault Park in Mt. Lookout. If the birthday is in the fall, you could go to Sunrock Farm, which is always a lot of fun for babies and kids. They offer tours of the farm and, of course, playtime with the animals. If you'd rather do an indoor party (or the weather requires it), Sunrock Farm also has indoor barns and party rooms. Otherwise, I suggest a simple pizza party at a local restaurant with a party room -- two examples are Snappy Tomato Pizza and Pizza Tower.