My wife and I maxed out our retirement accounts for the first time last year, and this year we're doing one better - we've got enough left over that we've had to open a taxable account!
To make matters better, we discovered recently that due to a couple of unexpectedly high-income and low-spending months, we had quite a bit more to start the taxable account with than we expected, so we can start right off with admiral funds. What a nice surprise!