Rain driving is an EXCELLENT learning tool. IMO, it separates the men from the boys. I remember driving an entire weekend in low 40's/high 30's in the rain. That event really fixed my throttle smoothness issue as well as really improving my looking and thinking ahead.
I find the worst part about rain driving is when its drying out. Because you're going a little faster and really not sure if there's more grip...before you know it your sawing the steering wheel trying to save it.
If you think RA is slick in the wet...try Motorsport Ranch in Cresson, TX. The dry line is like an ice rink.
2013 F30 328i Melbourne Red
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red