I don't know enough about lattice design to tell you about that.
In terms of analysing the data, I would put the data all into one table (easiest might be to use excel to input the data and then bring that in in a proc import).
You'd probably have the following columns:
Location, Genotype, Replicate, whatever parameters/performance you've measured
Then when it comes to analysis you can group by location and/or genotype in your analysis in different ways in order to analyse interaction effect etc