Methods to find optimal integration sites within a plant genome are provided. More particularly, a plant is transformed with a target site having an expression cassette comprising a nucleotide sequence operably linked to a promoter active in the plant. The target site is flanked by non-identical recombination sites. Transformed protoplast, tissues, or whole plants can be tested to determine the levels of activity of the inserted gene. By comparison of cellular activities of the gene in different insertion sites, preferred integration sites may be found wherein the gene is expressed at high or acceptable levels. These plants can then be utilized with subsequent retargeting techniques to replace the nucleotide sequence with other genes or nucleotide sequences of interest contained in a transfer cassette.