LLC or S-corporations are not taxable entities - any income (including capital gain from the sale of the investment property) will be passed through to members and will be taxable on individual tax returns based on total income, filing status, deductions, etc. - up to 35%.
If that is a long term capital gain (for properties held more than a year) - the reduced tax rate would apply - 15% if the taxpayer in 25% tax bracket or higher, and zero (for 2008) if the taxpayer if 15% tax bracket or below.
C-corporation would pay its own income taxes based on corporate tax rates based on taxable income:
below $50,000 - 15%
between $50,000 and $75,000 - 25%
between $75,000 and $100,000 - 34%
between $100,000 and $335,000 - 39%
between $335,000 and $10,000,000 - 34%
between $10,000,000 and $15,000,000 -35%
between $15,000,000 and $18,333,333 -38%
above $18,333,333 - 35%