Essex have done well with staging Women's T20 games at ECG in the past but we can't always expect to get them notwithstanding the decent attendances, other Counties (non Test ones) also merit big games so I suppose Derby & Leics deserve on that basis alone.
For the future though we really need to get this Ground business sorted or we may risk missing out in future, for the record I think we should stay where we are as the advantages will outweigh the disadvantages but we have to get a move on.