Yeah, MoMBA is right off of Area A (? Might be Area B). It's definitely going to give you more technical stuff than John Bryan and some more significant climbing and downhill, but John Bryan is pretty kickass in it own way, IMHO. Lots of tight twisties, the ability to carry tons of speed (albeit pedal generated rather than gravity fed), an opportunity for a good steady cadence work out, and a number of pretty nice ramps.
Weather in April will most likely be anywhere from the low 60s/high 50s to 80 for highs and pretty unpredictable as far as precipitation goes.
MoMBA will probably have better trail conditions in general and has the advantage of a daily recorded phone message letting you know if the trails are open or closed.
John Bryan definitely seems to stay wetter, longer. I've never seen the gate to the trails at John Bryan closed even when it should be.
MoMBA is probably going to be a 10-15 minute drive from you, John Bryan more like 30-35 minutes.
Caesar's Creek is probably more like an hour or so. I haven't been there since beginning of last fall, but large parts of it were an eroded mess. There were some cool tight spots and switchback descents punctuated by massively rutted, straight downs/ups.
Harbin Park is another one you might want to check out closer to Cincinnati, sort of in the same vein as Caesars, assuming you get some dry weather and you don't mind an hour to 1:15 drive.
Mitchell and England Idlewild are really nice as well, but not nearly as much trail as either of your close options
+1 on making the trip to Versailles State Park in IN. Along w/ MoMBA it's probably my favorite spot for sheer variety and all around awesomeness within an hour or so of the Cincinnati area. It definitely seems to drain well and is really well kept. If I had to guess I'd say it would probably be a ~2 hour drive from WPAFB.
