Here is a great primer on tax & bitcoin for US residents
http://www.bitcointax.info/
In general, you will not be able to simply hold your bitcoins and then buy expensive items with it without capital gains, as it falls under a barter exchange code of the tax law.
You're "supposed" to declare any exchangable services at their market value, for instance, if your friend is a doctor and you are a painter, you can paint his house in exchange for a medical service, but you will both have to declare the market value of goods received to pay tax as if it were income.
Of course, some things you can quite easily get away with and I don't think are a big deal (e.g. exchanging an hour of tennis lessons for an hour of math tutoring). But buying a house or an expensive car is kind of a big deal.
If you want to not pay gains, your best option is to move to a low tax jurisidiction and cash out once you've established residency there (that process would take about 6 months). Stay for two years, then return. You'll have to decide if it's worth uprooting your life for the savings in tax.