The real world difference between 92 and 95% is negligable; however, upgrading to a variable speed blower is worth while.
Having a 2-stage (or modulating) gas valve will not save fuel but it will dramatically improve comfort.
If you run the blower full time, the more efficient blower motor will easily save at least $200 of electricity per year. (per furnace, 0.10 per kwh or higher assumed)
120k BTUs for each floor excessive - was a load calculation performed?
R40-R50 attic insulation is recommended these days. (In ontario minimum code is now R40)
If you get multi-stage furnaces, insist on 2-stage thermostats. (Note: new wires will have to be pulled)