I’d say stick to the 20” size as they are the least controversial when you’re flying international. You can check out this 20” wide body carry-on (http://www.briggs-riley.com/category...Upright_U420XW) from Briggs & Riley. It’s wider than a regular 20” carry-on bags, thus giving you more packing space while fitting in the overhead bin of most aircraft. I am not sure if you need the second piece as a personal carry-on (since you’re allowed only two pieces), but see if you like this messenger bag. You can wear it cross body and it has a slip through back pocket you can use to stack it on top of your rolling carry-on.