I'm trying to learn about the rise and fall of Rome and as far as I can understand, these two books combined do that fairly well. Do they not cover any time period that's important? And if they don't, what are some books that do?
Rubicon recently received some critical commentary in this sub from u/Daeres that you can read here. There are also top level answers from other users that discuss other works by the same author - offering criticism on broadly similar lines.
There are various other older negative reviews of Rubicon floating around this sub that you can likely find in a search, including one in which u/LegalAction recommended burning it with fire... I haven't read it myself, but I might look elsewhere if I were you.
Speaking of which, there is the AskHistorians book list section on ancient Rome. Which does recommend SPQR, among others.