Everything that I've need/use for a 5 to 7 days domestic trip these days fit into my 22" convertible MLC, with room to expand (once only in last 4 years on a vacation return, with gifts from extended relatives) - less is more. Once beloved UA never "lost" our checked bags, only "delayed" them to be re-united, many hours later on a 6AM LGA-ORD-YVR flight (it went to IAD instead ) and it was checked @ the F counter, ground agent came on duty must've drank bad coffee, with us as first ones waiting for her - luckily, we weren't going on an Alaska cruise that time as Mrs. L was really pissed off. Took them till next day to retrieve my bag on a non-stop JFK-SFO with plenty of time for it to be loaded onto the correct aircraft. Drove back to the airport in the morning as courier delivery would've taken more time.
Depending on the seaons due to bulky 2XLT sizing & ease of access inflight, I keep electronics & gadgets in my TB2 messenger bag or a slimline backpack (personal size) that's good by itself for a quick overnight trip with space for packing cube (S) & 3-1-1's.
Overseas, mainly CX but also other carriers have been good thus far with checked bags but limiting to 1 bag (typically allowance is 2 free bags, but intra-Asia is tricky, so avoid the hassle factor) plus a bigger backpack with 1 extra packing cube. Using a smaller notebook/laptop helps to keep things lighter overall & quick laundry...