Following its masterful purchase and disposition of the former Equity Office Properties Trust at the peak of the market, investors have a great deal of respect -- and interest -- in Blackstone's commercial real estate investments. So when the private-equity kingpin this week picked up Apple REIT Six Inc. for $1.2 billion to amass nearly 200,000 hotel rooms, or about 4% of the nearly 5 million hotel rooms in America, investors took notice.