I won't get into what camera I use for travel, since that's highly off topic on this thread, other than saying that I carry 20/28/50/105mm primes for the time being, mostly manual focus and of which one has close focusing capabilities. I also carry a 1.4x TC for the longest lens.
However, since I do travel a lot (5 weeks to assorted locations so far this year, and I don't know when I'll return home), the bag I use might be of interest. I bought the bag, a Lowepro Inverse 200 AW, by coincidence many years ago. The price is slightly more than $50 at the moment, so it's very cheap. I have no idea on how many journeys it's been travelling, but we are talking about 100+, on planes, buses, trains, boats, motorbikes, tractors etc. It's also been with me at well over 100 car races and other sports events and countless other occasions. It's pretty much been with me anywhere, every day the last few years, and it's been rolling down staircases, fallen off vehicles, been used as pillow etc.
For functionality, it features:
- Can be used as a shoulder bag, belt pack or handbag.
- Rooms one camera body and up to five lenses (one on the body) or two bodies and three lenses. Small lenses can be stacked, making room for more.
- Can take a 70-200mm f/4 or consumer grade 70-300mm standing.
- It has a flat top, which doubles as a desk when worn as a belt pack. Great when filling in immigration forms etc.
- Is compact enough to be carried inside a larger carry-on bag for air travel, leaving enough spare room for a weekend's worth of clothing.
- Has two external bottle holders and outside pocket for batteries etc. (I mostly carry my spare battery inside the bag though.
- Holders for two memory cards inside the lid (I travel with two cards in the camera and two spares in those pockets).
- Straps for a small tripod or Gorillapod underneath.
With a compact camera body, like the A7, it should be possible to modify the interior to room a tablet computer, but I haven't tried that. Be aware that the lenses I use are relatively compact (Nikkor AiS), and that contemporary AF lenses may reduce the number of lenses that can be carried.
Inverse 200 AW Camera bags, backpacks and rolling cases
There is also an Inverse 100 AW available, which might be large enough for an A7, but due to the smaller size it will also take fewer lenses.
Edit: When m4/3 was my main camera system, I often carried this bag with three camera bodies (GH1/2/3), one lens on each. That would probably be possible with A7 bodies as well.