You might have issues using Hotel Wi-Fi for auto cloud uploading as these usually require a separate web page acknowledgement to connect. If you are able to upload, yes, you can easily download the footage to your computer once you are home.
Quick Key is very fast, although the 5gHz on the Hero6 works pretty good for transferring to your phone. You shouldn't have any issues moving the files from your phone to computer, but the question I have is, how much room is on your phone to transfer the files?
I haven't tried it yet, but I believe the GoPro app is now supposed to be able to upload media to the cloud after it's been transferred over. If this is the case, then you should be fine.
As far as having enough space on your 128GB card, remember, if you fill this card it is going to be a lot of footage to review and edit. I believe in filming as much as possible, but try to keep the moments you capture short. I generally don't record for more than a minute at a time unless I really need to record longer. It just ends up being more footage that I never use and just end up deleting anyway. Personally, I think you would have been better off with a couple 64GB cards than one 128GB. This way you could of had one card for each week. Additionally, the larger cards (128 and 256) tend to be more prone to errors (I'm not saying you will have issues, but it's more likely).
What resolution/frame rate are you planning on shooting in? The conserve space and for faster transfer, 1080/60 will probably be best. 1080/120 for super slow motion shots and 2.7/30 for scenery, but primarily use 1080/60 for day shots and 1080/30 for low light. If you keep Protune off you will also conserve more space. With Protune off you still get great looking video and all the settings will be default. Some reviewers have also stated that they think low light looks better with Protune off.
