The only asset class that you can invest in with certainty is cash. You know what the deposit rate is at the outset. With everything else, there are loads of variables that can effect your return. It is impossible to tell you with certainty that any particular asset class or combination of asset classes with give you 3% - 4% per annum. Remember, for an average return of 4%, you can have a return of 8% and 0% in consecutive years.
On the asset classes you are talking about, Zurich Life don't do direct property investment, they never have. If you are in a Standard PRSA, gold won't be available either (it may not be available under the non standard contract either. Their website is down, so I can't check).
I'd keep it simple, bonds and equities.
Steven
http://www.bluewaterfp.ie (www.bluewaterfp.ie)