FAIRFIELD, NJ— In a deal value d at nearly $800 million, including debt, Prime Hospitality Corp. has agreed to be acquired by private equity firm The Blackstone Group. Prime Hospitality, which operates and franchises 256 hotels under the AmeriSuites, Wellesley Inns & Suites and Prime Hotels & Resorts brands, had its stock valued at $12.25 a share, a 42% premium to the closing price on Aug. 18. Blackstone has already announced its intention to convert 37 of the owned Wellesley inns & Suites properties to one of its Extended Stay America brands. The company also plans to maintain Prime’s headquarters operation here. The board of directors of Prime approved the agreement in a meeting today and the transaction is expected to be completed during the fourth quarter of 2004, subject to shareholder approval and other customary conditions. Prime also said it would launch a tender offer relating to its 8.375 percent senior subordinated notes due 2012.