Welcome to ER, Brian
One of the upsides of the hybrid heating system you propose is that the NG system could keep the house at a minimal temperature, while the electric baseboards would kick in only in those rooms and only when extra heat is needed.
But since you are still in the planning phase, you can take into account more options. For example, one of the most efficient ways of heating (when passive solar isn't enough) is to use
hydronic floor heating with a
heat accumulator. The heat accumulator would be charged by solar panels and a heat pump. AC_Hacker has an
excellent thread which shows how easy and cheap it is to make your own ground source heat pump.