I gave the Lesco Park & Athletic mix a try last season with good results. Blends in well with existing lawns, nice dark green and filled in well. I don't have the exact mix handy, but it's about 1/3 each rye/BG/fine fesque if I recall. About right for lawns here in CT. For some lawns with persistent bare areas due to poor soil condtions that the customer does not want to correct, I used the TTTF/rye mix, Teammates Plus. I was hoping I could get something to make it through a season and get established but in general a dry period and lack of watering wiped that out (most people here don't irrigate).
For some reason, it's common practice here for developers to put down topsoil and final grade the lawn first, and then later do the septic system install without putting topsoil down again...I see it over and over. The grass is supposed to be greener over the septic system!!