For bookkeeping, it is simply EASIER if you use each card exclusively for business OR personal, don't mix.   

Have been using them exclusively for about 3 years.

As the original note as we all know stays with them and their credit.In Portlandia I personally created my rental portfolio from 2002 to 2008 using sub 2 exclusively and most were in foreclosure ( before the foreclosure rescue laws changed). and generally I did not buy anything that did not have at least 20% equity. 

I have been recently been approached by family members about purchasing a vacation cabin in Okoboji, Iowa at Bridges Bay resort (www.bridgesbayresort.com) to be used exclusively as a rental/investment property.  

Part of it is taxable and part of it is eligible for capital gains exclusion under Section 121. 

If you sell it in a year, it will still have been your daughter's primary residence within the timeframe to use the primary residence exclusion to avoid most/all of the capital gains you would have incurred. 

@Matt Ridenour  I know that Royal Legal Solutions has a CPA on staff that specializes in tax strategy and planning and he and his team work exclusively with real estate investors. 

,You are confusing this with the Section 121 Exclusion for Sale of primary residence.

Then sell it and take advantage of the $250k (single) /$500k (married) 121 exclusion as well (which is even better than 1031 in that your gain is tax-free not merely tax-deferred) as well as 1031 if your gain is in excess of $250k/$500k.

@Robert Wong If you move back into your rental and convert it to a primary residence and live there for at least two years you will be able to qualify for the 121 Exclusion.