Real estate investment trusts are on the move again, and Ross Smotrich, an analyst at Barclays Capital, thinks now is a perfect time to buy blue-chip REITs at bargain prices. (For another take on REITs, see page 108.) He likes Boston Properties ( BXP, 50) , which owns classy office buildings like Boston's Prudential Tower, San Francisco's Embarcadero Center and, in Manhattan, 399 Park Avenue, Times Square Tower and Citigroup Center.