does this rate fluctuate based on assets? I know that it's set to go up if the tax cuts aren't renewed, but is it the same for everyone?
Generally, the rates for capital gains are based on your marginal income tax bracket as well as the length of time the asset is held. If you are in the 10% tax bracket, then the long-term capital gains rate is 0%. If you are not in the 10% marginal income tax bracket, then the long-term capital gains rate is 15%.
There are different rates for short-term gains (on assets held less than one year) and for long-term rates (assets held for longer than one-year). In the case of real estate assets, you need to consider that the first $500,000 in gain above your basis for your primary residence if owned jointly (purchase price plus improvements plus real estate sales costs) is exempt from any capital gains tax.
Now, what makes sense for you will depend on several factors as well as the type of asset (real estate versus non-real estate). If your income places you in the 10% tax bracket, then selling assets now to realize the gains may make sense since there is no capital gains tax. But beware of selling too many assets that then push you above the 10% income tax bracket because then you go from 0% capital gains to 15%.
And next year, there is the added surtax of 3.8% on those who have high adjusted gross incomes as well as a high amount from non-wage/non-earned income sources (like investment income).
You may be best served by engaging a qualified financial planner who may be able to help you sort out the tax planning issues specific to your situation.