I've watched some game play footage of Rome II: Total War and it looks amazing. So much more depth than the original.
I can't wait for your LP to start. I hope you will consider doing a long campaign or whatever the equivalent is. Your strategy LPs are amongst my favorites. Your Rome II LP will be epic.
Sorry, but Rome 2 is a huge disappointment. If you are lucky, you will manage to play it without lags, crashes, FPS drops, glitches AND you will like all new features(no geological tree, generals dye too fast etc). But even then, you will have to deal with terrible AI, which doesnt give any challange even on legendary difficulty. I would wait for a few months at least.
If you want to make TW LP, there are 2 biggest TW mods out there. Roma Surrectum for TW: Rome. And Stainless Steel for TW: Medieval 2. As you can see, forums are still alive, this are not tiny improvments, huge 5gb mods being developed for years. And they both drastically improve AI. You will have way more fun playing this mods then Rome 2.