Angel investors are hands on folks. Angels are probably the most expensive way to raise capital next to getting money from friends and family. The reason most angels do so well is because they are hands on.
Having said that, there are Angel groups all over the country. If you dont have the time to dedicate to investing, but just want to grow your money, I suggest you attend some of these events. Sometimes you will find a startup that really does not require the coaching but is in need of startup capital. An investment with a startup that is already got the wheels turning but only needs "growth" capital might be a good fit for you. The more mature the company, the less risk, and thus less return.
Making friends with other angels will help you out, but these guys are not investing their time for charity. If they are using your money for an investment, then trust me they are going to take a cut of your earnings.
Investing in inventory is another option. For example, giving angel loans to small car dealerships may be a safe bet, because you are not investing in the physical business, but rather are investing in inventory of which you can hold titles as collateral for your loans.
Last, and easiest option is to give your money to a VC firm and let them make money for you. Wont give you the highest return, but its probably a very safe bet since its going to be spread among multiple ventures.
If you have 250k + to invest, then you may consider hiring an experienced CFO or someone with good Entrepenuer expereince to help manage your startup investments.