Personally I'd like to see the show end with the Cylon war starting. Even if it had to skip a few years, we could at least see some stylistic and technological development.
It should end with the troops leaving for war, including Young William.
It should have an early 60's cold war feel, with growing paranoia.
Technology will start dumbing down to deal with the Cylon threat, think London during WW2 when the lights had to go out.
As the aircraft start to develop, including the vipers, I'd like to see some of them in polished aluminium as per the Korean War era (camo is no use again Cylons after all).
Just a nit pick but I'd like to see more of the unusual styled US cars, not just European (this show is seen around the world) think Studebakers and Virgil Exner styled Chrysler products, in particular the 60's dodge air force trucks, they would fit right in with the style. The viper pilots should have the 50's styled helmets that William is holding in the photo with his two sons, at least at the start of the war.
Ok I better stop, but this show has so much potential, thank you Ron Moore, for the only two reasons for me to watch TV.

It just started! Why such a hurry?!

Considering they had no idea how to end the last series, it seems likely he'd have no idea this time too. Will it be as awful as the conclusion of Battlestar? That's tough to top...

If they were to present some flash forward style of narrative, I wouldn't mind seeing the 5... otherwise, I just don't see how they can do it. Having the other actors who the numbered models are based on would be fine, but not the 5.

As much as I'd love to see the BSG mythology expand, as a stand-alone series, I believe it should end right at the beginning of the Cylon uprising, when the audience becomes aware that humanity is about to get some big time comeuppance. This also means that there should be no Final Five since they come with a load of backstory to the uninitiated. Their introduction is also not a conclusive way to end the series, as they segue right into the opening of Battlestar Galactica. Again, the series should have its own beginning and end.

We already saw the scene where the Final-Five came to the colonists in Razor from Bill Adama's perspective. That's when the war ended and the cylons disappeared for 40 years. Adama was aged at least 20, so if they want to include them in the plot they most definitely need to do a few time jumps.

There would have to be some serious time jumps for the Final Five actors not look too old to play the parts. Personally, I wouldn't mind a time jump of 3 or 4 years so they could get rid of the kid playing young Adama.