I have both a checking account and a brokerage account through Schwab. Originally, I opened the brokerage account because it was required for the checking account. A few months ago, I decided to buy CD's through my Schwab brokerage account because I wanted to have easy access to the money, and transfers between the two accounts are almost instant. I like the trading set up within Schwab better.
On the customer service front, I really like their phone support and everything associated with that. The receptionist at the local office took some time to get used to me since I am not their normal clientele, but now she is nice to me.
ETA: Looking through my Vanguard account, I realized that you need to have a minimum of $10,000 to invest in CD's. This was too high for me to build my CD ladder, so that was the main reason that I went with Schwab.