There’s no need to be concerned about Microsoft’s encryption. By default Microsoft Office uses AES-128 bits with 100,000 iterations – this is extremely secure [source].
How long will AES-128 take to crack? Well, that depends upon the length of your password but to give you an idea about 14 billion years according to one researcher [source]. I estimated it to be about 12 billion years.
So comparing AES-128 to AES-256 is pointless because in reality neither are going to be cracked any time soon. It’s like asking which is easier to swim: the Atlantic or Pacific?
One thing to bear in mind though: in your situation you’re seriously compromising your security by opening your files on a hotel (i.e. non-trusted) computer. If there’s a key-logger installed, they’ve got your password. If there’s file recording software installed, they’ve got your file and your password. If there’s security cameras overlooking your screen, they’ve got the information. No amount of encryption will help you here.