Less than 300
More than 1600
We live in less than 400sq/ft net in HK, and I do find this a bit too small for 2 people, though. It's pretty annoying when my partner can't help prepare dinner, because only one person can be in the kitchen, or if I can't grab something out of the bathroom while he's in it. It's been good, though, to have this experience and learning how it is possible to live like this (and with less stuff!). We have managed to have a piano and other large things without cluttering the space too much, but doing so took a painful amount of time to organize. Thankfully we have a very good flat layout with a walk-in closet instead of one of those mini-HK one bedrooms.
What I find really luxurious and nice is to have an en-suite bathroom and an extra bathroom for any potential guests.
When I arrived in HK I lived in a 1,900 sq. ft. net flat, alone! I felt I needed a compass to find my way, so I moved in a 750 sq. ft gross.
It's not so much the size I miss the most, but the privacy that goes along with it. I don't need a lot of junk, but I miss having multiple floors, basements, garages and backyards.
I hear people saying how Hong Kong is tough on marriages...and I think most people assume that is due to work stress, long hours and infidelity issues. However, I think Hong Kong can be hard on marriages because everyone is forced to live in such tight quarters. Back home I would go to the garage to work on the car, go mow the lawn, the wife could garden or I could simply retreat downstairs to watch the ballgame. Even guests that I have come into town seem to get on my nerves faster...a result of not as much privacy and personal space.
That was a hard adjustment for me...but now I have a much needed rooftop which helps a bit in that regard.
If they are budget-challenged, you might offer to pay for their accomodation (if you can afford it).
Other ideas - suggest that you "all go somewhere together to take advantage of being in Asia" - e.g. beach resort in Phils; tour of China; Phuket - anywhere really where you can all stay in Hotels and pay for your own rooms! That might reduce the squash time down to something livable.
Failing that, I suggest an "urgent business trip" should "suddenly" be necessary right in the middle of the visit, leaving you only enough time to say "hi" when they arrive and "bye" as they leave..... (been there; done that! )