If it is not an emergency or critical situation,

 

are the hospitals in Bangkok open on the Weekends to get good experienced doctors and care (eg. Nursing, lab, xrays etc),

 

Or, is it better to go on the Weekdays, Mon-Fri, say between 8am -5pm, when I assume all staff are working.

 

Or, it does not really matter what time, day or night, to go to the hospital as good services are available 24 hours.

It will depend on the hospital involved but normal hours start at 0800 or 0900 and extend to about 1800 most places - some clinics will remain open longer and they will normally be open the normal hours 7 days a week but admin work may be limited on weekends/holidays.  Most larger places have 24 hour emergency room service but their normal clinics would not be staffed.

 

Private hospital outpatient depts are open evenings (usually to around 8 PM, sometimes to 9) and weekends and indeed, the best specialists are often available only then as they are often at government teaching hospitals during weekdays.

 

You can see specific doctor hours on the websites of most private hospitals. You should do some research and chose your doctor, don't just show up and rely on the clerks to decide for you.

 

Government hospitals: public channel is  only Monday-Friday 8 - around 4 (best to arrive very early morning as queue fills up quickly) but there are often after hours clinics from around 4 - 7 Pm and on Saturday mornings. However tests and such may not be available then just consultation.

 

In all hospitals emergency rooms are open 24 hours.

 

It is better to go on weekdays during normal working hours,  preferably not on a Friday afternoon. 

X-ray department,  lab etc will be working.

And staff is never too happy if patients show up at 10 pm on a Saturday night who could just as well have come on Thursday,  Friday or Monday. It puts you into a certain corner right from the beginning. 

 

As Sheryl said, "You can see specific doctor hours on the websites of most private hospitals. You should do some research and chose your doctor, don't just show up and rely on the clerks to decide for you."