Just on twenty years "on the road" here. Not working for the "big four" but multinational IT companies.
My travel has been between Perth and NZ and PNG in the main but also several long stints around Asia.
Most of the travel has also been with a "base" in the country I was working in such as an apartment, and sometimes a vehicle, that was kept even when I wasn't there which made things slightly easier. Far better than hopping between hotel rooms also makes it easier travelling between countries with just a laptop bag!
My experience is the first thing that gets negotiated out of any new client contract is J travel. It's just the way it is.
Have I enjoyed it? Hell yes! Would I have preferred to have stayed in my previous government job for those twenty years? No way! I have seen and experienced some amazing things, quite often with the company or the client paying! The perks have been great in such things as FF and accomodation points. The trips with Mrs Tallfont that have been funded, in the main, using some of those points have been great experiences.
But there is a downside. Missing a lot my children growing up, graduations, birthdays....the list goes on. Quite often you cannot get the company to arrange projects around your requirements! Then there is the catching a taxi to the airport at 10pm on a Sunday night to get the "red-eye" across the country, followed by another flight the next day! I sure don't miss that.
I was doing this up until March this year when of course COVID-19 became very real and borders were starting to close. I made it back to Perth just in time to do my 14 days at home. I haven't been on an aircraft since (although I did get a QF bar cart to remember some of it!
) Very happy working remotely now with the occasional Zoom meeting thrown in to keep some normality going!
Back to the OP questions.
Travel does get tiring and sometimes you wish you weren't having to do it however my experience is you work around it. You would probably soon work out if you like it or not.
As mentioned I have seen and experienced some amazing things and also met some great people and made some lifelong friends.
With regards the "big four" not having worked for them I cannot say much about the out of hours work. I do have several friends that work or have worked for them and, without fail, they all say that they work long hours and it's pretty high pressure. Too old for that these days!
Hope it all works out for you. It can be "living the dream" if you do it right.