I have always had a portfolio of mixed ideas. I have enjoyed buying and then holding really good businesses that get inexpensive every once and a while (JNJ, BRK, etc..).
I then have a decent percentage of capital invested in other ideas i.e. warrants, preferreds and common stocks of smaller businesses. However, this is not a buy and hold area of my portfolio. For example, I have been in an out of various preferred securities numerous times in the last 4 years.
Then I always have excess cash, because I never know when I will have a chance to take advantage of public or private opportunities.