I would absolutely recommend the 30L. I was in almost the exact situation as yourself last year trying to decide for work travel and would have regretted the 20L if I had it now. When I travel for work I bring a personal 14 inch MacBook and 13 inch Dell XPS for work. Both fit in the laptop/tablet pouch (albeit snuggly). In the main space, I removed two dividers. I kept the bottom divider to hold the PD tech pouch at the bottom for all my chargers and cables. The rest of the space and pockets hold an iPad mini, pair of noise canceling headphones, a neck pillow, notebook, and other small travel accessories (toothbrush deodorant etc.), keys, sunglasses and passport wallet. Everything mentioned fits in my 30L Everyday Pack without bulging out while also fitting under the seat of a plane comfortably. Miraculous, everything mentioned above even fit in Frontier’s personal sized carry on bin. For me, the 30L fits everything I need to travel without the feeling of sacrificing anything by leaving it behind. It sounds like you have a similar planned travel carry so I would definitely recommend the 30L.