I've never owned them, but I was under the impression that the Tilliums were fairly sturdy and, unusual for carbon wheels, fit for everyday use.
They're a bit heavier than other carbon hoops, but they're filled with a semi-dense foam (as opposed to the usual hollow carbon dish) and apparently a smooth ride.
I think they use a proprietary spoke.
On that note, dismissing the Zipps for having busted a spoke on you isn't really fair; you can expect to break a few spokes on any wheel over its lifetime. As xavier pointed out, Zipps use standard spokes, which makes servicing them easy.
If there's a problem with Zipps, it's that tubulars are the source of their fame -- Zipp clinchers have undergone a few redesigns, and though they're apparently now much improved over the initial 2001 (02?) model, it remains to be seen if they're a wise buy.
For the price of Tilliums (about $800 USD), one should note, you can get a pair of Ksyrium SLs, Campy Eurus, Velomax Ascent IIs, Rolf Prima Vigors or Rolf Prima Elans. Among carbon wheels, what's available at that price point (really, just the Tillium) is a less obvious value than these excellent aluminum rims.
Good luck deciding.