If some commercial real estate experts are feeling optimistic, then SL Green Realty might be downright giddy. The landlord said that it’s seeing an uptick in leasing activity — and it plans to take advantage of the newly favorable scenario by raising taking rents on its upscale properties by as much as 7 percent, according to Crain’s. Steven Durels, executive vice president with SL Green, said that the company’s premium properties are getting more attention for the first time in a long while. “We are getting a lot of offers on our better spaces,” Durels said. “That hasn’t happened in over a year.” While the taking rent uptick will affect just 30 percent of the landlord’s 25-million-square-foot, 30-building portfolio, the policy change will apply to some of the company’s most high-profile properties, including the top floors of 810 Seventh Avenue and the tower floors of 100 Park Avenue. SL Green says it has the clients to back up its changes — while the first half of 2009 had been dismal for the landlord, the last two quarters of the year resulted in a 56 percent surge in leasing activity over the beginning of the year.