I had a mostly good experience in a mental health hospital, it was like being on vacation, but don't expect too much. We were mostly just well-fed and given pills, there were some other activities too, like 'work therapy' where people knitted or crocheted or painted or such, there was some 'group therapy' but it didn't seem very helpful to me... 'Art therapy' was totally not what I expected... There was some 'sports' too...
Not sure if they'd allow you to experience any of these things or talk to people there, yeah...

Maybe you'd have better luck trying to google for people talking online about any places you might consider? In our country there's a forum where people discuss these things too... Maybe people have even talked about it here on the forums or you could ask here? (Not sure if it's allowed or not, might ask a mod 1st)

Often people who signed in by themselves did go to 'open ward' immediately (those 'committed' there usually went to the 'closed' ward first), there are these workshops and freedom to go home on weekends and such on the open wards... This may be different in different countries or hospitals though-?