"working for a pretty good tech company" ... "do not have access to a 401k."
Personally I find those statements contradictory - a good tech company should provide a 401(k) with company match. If they can't even do that, their benefits and concern for employees must also be lower than the better tech companies - just my personal view. The idea that you're leaving it soon suggests you might even agree, but I digress...
Right now the S&P 500 has 2% dividends. That means with a $10,000 investment in the S&P 500 you would expect $200 in dividends per year. If you make less than $400k / year, the IRS taxes you 15% on qualified dividends. So the IRS would want $30 / year of your $10,000 investment. Meanwhile if you pick the wrong place to invest, you could be paying 1% ($100 / year) in annual fees instead of 0.05% ($5 / year) at Vanguard.
As a tax strategy, buying and holding a passive index fund makes sense. Where an active fund buys and sells, realizing capital gains, a passive fund makes every effort to avoid that (people selling / exiting the fund may require the fund sells stocks).