"Buy term and invest the difference" is certainly the standard recommendation, and for good reason. When you start looking at some sample numbers the "buy term and invest the difference" strategy starts to look very good. Here are the rates I found (27 yr old in Texas with good health, non-smoker, etc):
$200k term life: $21/month
$200k whole life: $177/month
If you were to invest the difference in a retirement account for 40 years, assuming a 7% rate of return (many retirement planning estimates use 10%) you would have $411,859 at the end of that period. (If you use 10% that figure jumps to over $994k.) Needless to say, $400k in a retirement account is better than a $200k death benefit. Especially since you can't get the death benefit AND the cash value.
Certainly one big difficulty is making sure you invest that difference. The best way to handle that is to set up a direct deposit that goes straight from your paycheck to the retirement account before it even touches your bank account. The next best thing would be an automatic transfer from your bank account. You may wonder 'What if I can no longer afford to invest that money?' First off, take a second and third look at your finances before you start eating into that. But if financial crisis comes and you truly can't afford to fund your own life insurance / retirement account then perhaps it will be a good thing you're not locked into a life insurance policy that forces you to pay those premiums. That extra freedom is another benefit of the "buy term and invest the difference" strategy.
It is great that you are asking this question now while you are young. Because it is much easier to put this strategy into play now while you are young.
As far as using a cash value policy to help diversify your portfolio: I am no expert in how to allocate long term investments after maxing out my IRA and 401k. (My IRA maxes out at $5k/year, another $5k for my wife's, another $16.5k for my 401k.) Before I maxed that out I would have my house paid for and kid's education saved for. And by then it would make sense to pay a financial adviser to help you manage all those investments. They would be the one to ask about using a cash value policy similar to @lux lux's description.
I believe you should NEVER PUT YOUR MONEY INTO SOMETHING YOU DON'T UNDERSTAND. Cash value policies are complex and I don't fully understand them.
I should add that of course my calculations are subject to the standard disclaimer that those investment returns aren't guaranteed. As with any financial decision you must be willing to accept some level of risk and the question is not whether to accept risk, but how much is acceptable. That's why I used 7% in my calculation instead of just 10%. I wanted to demonstrate that you could still beat out whole life if you wanted to reduce your risk and/or if the stock market performs poorly.