With TIAA CREF you can usually "annuitize" your accounts when you're close to retirements. That way you (theoretically) get the benefit of higher returns when you have a longer time horizon, then less risk when you retire. So no need to sign up for the trad annuity just yet unless you're very close to retirement.
My 403b is also with TIAA CREF and IMO those are good index funds. I have 25% in their bond index, 53% in their Russell 3000 equity index, 22% international equity index. You asset allocation will differ depending on age/risk tolerance etc; check out the Bogleheads wiki and the rest of the internets for advice on allication. I picked the Russell 3000 over the S&P 500 because of the broader diversification. These funds are not a mix of bonds/equities; they are just one asset class. An index fund is an index fund; they all track the index pretty well, as you'll see from the graphs on the TIAA website.
Personally I don't think the life cycle funds are worth the extra expenses unless you're totally unwilling to rebalance your allocation annually.