There are thousands of ways of doing this, so no one can say what's best for your purposes. Peter McCulloch's example is one very simple approach, but the distribution has some artefacts you may not like (occasional almost-synchronous notes is just one of them).
If I posted all the examples for random rhythms I've written, I would exceed the 40kB post limit by several orders of magnitude and we'd have to wait for Andrew to decide whether or not to let it through. Instead, I'll just point you the Examples page on the Litter Power web site: . Poisson Rhythms, Pink Counterpoint, and even the Instable Oscillator will give you plenty of ideas. You'll need at least the Litter Starter Pack (free) to use them, but if you're at all interested in randomness, you really ought to take a look at Litter Power.