I agree with most everything in this thread. A lot of good insight. I absolutely love beyer mics and you really can't go wrong with any of these mics. I use all three mics mentioned here virtually every day. Here's what I hear:
M69 - rich mids, sparkly top end. Not too much low end. Great on guitar amps, vocals, horns, and snare top.
M88 - super lows, strong mids, smooth top. Bass drum is where this mic really shines. Also great on trumpet, vocals, percussion, and bass cabs. Proximity effect makes this mic not a great choice when focus is needed.
M201 - not as colorful as the others but very beautiful sounding and useful mic. Classic snare mic, but works well on bass drum beater side, acoustic guitar (especially nylon string), and trumpet. Kind of like a 57, but without the harsh highs, and more proximity effect. Also much greater rejection than a 57 and much smoother.