I did 6 weeks in Shanghai with just a single 22 inch soft sided carry-on suitcase, which held my briefcase and laptop plus clothes. So doing 10 days in summer should be a breeze.

The features you need depend on your packing style and what you need to take.

In my case, I'm a flat/bundle packer, so I prefer single compartment bags with few "features." However, limiting the number of shoes you bring will make you packing much easier no matter your style. Also bringing a foldable bag to is always a good idea too.