Vanguard funds will have lower expense ratios than TRowePrice, however their brokerage service VBS leaves quite a lot to be desire.
On regular mutual funds vs ETFs:
No-load funds have no commissions to buy/sell and you get the end-of-day NAV whenever you trade. No agonizing worries about limit orders, best prices, whatever. Some Vanguard funds have a small purchase fee of 0.25%.
ETFs trade like stocks, so you can have the following extra expenses:
1. Commissions (can be avoided by using a broker with free trades like WellsFargo).
2. Bid/ask spread: One does not buy at the NAV, nor sell at the NAV. There is a small spread that the market maker pockets. This can be 1 or 2 cents on a $30 stock or an extra 0.03% or more.
3. Premium/discount to NAV: Sometimes the bid/ask quote is a bit aways from the intraday NAV.
4. Any dividends automatically reinvested are usually a day or two later and the broker decides how much you pay for the reinvested shares. This is somewhat different from the standard mutual fund where shares are bought at the NAV on the same day as the distribution.
I like to use ETFs for my equities and use regular funds for my fixed income assets. I like to pick the price I am willing to pay, track tax lots, and do tax-loss-harvesting. I find all this easier with ETFs.
For more help with using Vanguard from folks who use Vanguard, check out:
Bogleheads :: View Forum - Investing - Help with Personal Investments