If you're getting a 401K match, it is still a good deal even if you plan to spend it at some point. When you leave your job you can take the 401K money with you, either roll it into an IRA or you can cash it out. If you cash it out you pay a 10% penalty, plus pay income tax on the money. If you got a %100 match on the money you contributed, and since you did not pay income tax on it in the first place, you make out after paying the penalty.
For example, you contribute $500 in a year, employer matches that, you now have $1,000 (plus any investment growth), you leave and cash out, pay %10 penalty, $100, pay income tax, let's say in your bracket %15, so $150. You walk away with $750. And remember if you had not put the money in the 401K you would have paid income tax on it anyway.
It's free money, take advantage of it.