Barring any serious family resentments (in which case I'd totally skip the trip) I think it sounds amazing for your lil crew! We haven't taken DS overseas, but he's been in many a long road trip (including the every night another town type). The most recent he was 15 months and he did awesome (he's a very spirited kiddo, so we weren't sure how it would go)!!! Being mobile, he walked until tired or until we were somewhere he needed to be in the Ergo. There is so much to see, so many new and exciting sights, he was never bored! It really broadened his lil world - even if he won't remember, it made a big impact, you know? And DH and I enjoyed it so much more, both knowing he was safe AND being entertained by his reactions. I'm also big on teaching him from a young age that the world is his home, and that he can trust that we travel in a pack.
Practically, I would consider whether your lil one likes babywearing (love Ergo for this - can switch to back carry so they can see or front to nurse on the go) and how flexible she is about when/where she'll nap. Also, if you'll have some down time from activities to process your day. IME, many home routines can be preserved pretty well to give security as well (bed/bath routines, etc.). Good luck!!!!