I know this is an old question and the OP has probably already done the transfer, but this answer may be useful for posterity.
I have done a transfer from Schwab to Vanguard and it's a delicate process to handle correctly. Vanguard Brokerage Services either charges or does not charge a fee via FundAccess depending on the individual fund. You can use Vanguard's fund screener to find out if your individual funds are transaction fee funds at Vanguard. Schwab Funds are transaction fee funds at Vanguard, and it will cost $35 per transaction (as of this writing) to sell their funds at Vanguard. Other fund families have no transaction fee at Vanguard, for example American Funds and many front-load funds have no transaction fee from Vanguard to sell (though they may have a redemption fee charged by the fund company; as always, read the prospectus).
Also be aware that Schwab charges a fee for transferring your account out. When I did it in mid 2013, it was $50. Additionally, if you do the transfer as a "liquidate and transfer", they will charge you the broker-assisted trade fee for each fund they liquidate, which was $25.
Another thing to be aware of is if your transfer is occurring around the end of a quarter, if you hold your funds at Schwab around the ex-dividend date but they're transferred before the dividend comes in, the dividends will end up in your Schwab account. The funds will need to have been transferred to Vanguard prior to the ex-dividend date. This is tough to time, especially if you hold bond funds, as it may involve mailing in paperwork and some funds (i.e. bond funds) pay interest and dividends monthly. With electronic transfers, these additional bits of income can be swept over but in the case of Schwab to Vanguard it was done by a paper check (literally, Schwab sent Vanguard a check via USPS) and those are not eligible for automatic sweeps.
When transferring from Schwab to Vanguard, you will want to liquidate any Schwab mutual funds you don't intend to hold yourself first, along with any which are transaction fee funds at Vanguard but not at Schwab. You might consider swapping the mutual funds for ETFs where you can to minimize time out of the market, but note that while Schwab ETFs are commission-free at Schwab there is a commission to sell them at Vanguard. The commission on selling ETFs is much lower than the FundAccess fee for selling mutual funds. A good idea might be to liquidate all your mutual funds into 2 or 3 index ETFs to approximate your portfolio such as the Schwab Broad Market ETF (SCHB), Schwab International Equity ETF (SCHF) and the Schwab Aggregate Bond Market ETF (SCHZ). Alternatively you may just pay the commission at Schwab for Vanguard ETFs before transferring as there is no commission to sell those at Vanguard if you want to swap them for mutual funds instead. Check to see who has the lower commission for ETF trades. This will minimize time out of the market and fees.
Generally speaking, and it depends a bit on the size of your account, it's better to accept the trade fees than to spend time out of the market.
Also consider the tax impact if this is a taxable account. If you are happy with the funds and don't intend to sell them soon, an in-kind transfer will not incur taxes.
Once that is done, transfer the entire account "in-kind." Also note that in most cases there is a delay of up 3 days to settle the sale of mutual funds through Vanguard Brokerage Services and the sales will have to settle before the money is swept into your Vanguard Money Market Fund. You won't be able to buy Vanguard mutual funds until the 4th day after the sale. Put simply, if you sell funds at VBS on Monday you will be able to buy Vanguard funds on Friday.