I'm not sure I have a lot to add here and this question is kind of old, but as I would like to use the search function and I suspect other people sometimes have this question, I will contribute from the peanut gallery.
As other's have said - it really depends and it's really boring.
1) it's a place to be safe. i'm sure a truly driven person could hurt or kill themselves on a psych ward but they make it pretty hard.
2) it's a place to hopefully relate with people dealing with similar issues.
3) there is very little/no privacy. someone checks to see what you are doing every 15 minutes. you generally can't have much stuff - a few clothes, books, papers, that's about it.
4) the places I have been, there was not the possibility to go outside, unless special arrangements were made.
Fortunately, I have not ever regretted going to the hospital. It was helpful for me in a lot of ways but I'm unsure that it has fixed anything for me in the long term (as evidenced by the fact that I am on this forum?)
The TL;DR:
I think I have been hospitalized multiple times when I have felt myself very close to trying to kill myself. I was hospitalized in a rural area of the US voluntarily with the help of my doctor when I was suicidal. The advantage of having a doctor help, I think, is that they can make reasonably sure there is an inpatient place for you when you go and you do not end up being held in an ER hallway for 72 hours.
Once I had to be admitted through the general ER . This was the worst part. It was very stressful and I felt embarrassed that I was just another nut coming through the ER. I went alone. The nurses were quite rude and dismissive at a time when I was incredibly fragile and it sucked. I had to give them my clothes, shoes, phone, etc and wear paper hospital scrubs, get a blood draw. A psych doctor came and spoke to me and asked if I wanted to be admitted and I said yes.
At one hospital I spoke to the admitting doctor on the phone and was then asked to come to the general waiting area and someone from the psych ward came down and got me. This was the nicest and least stressful way to be admitted, I think. At this hospital I was allowed to keep my phone and after my boyfriend met my doctor he could come most days and we could go for a scheduled walk together outside. This hospital was a research hospital connected to a university. I'm not sure if that mattered or not, but it was the least "rigid" hospital.
Most recently, I was hospitalized in a larger hospital in an urban area. I had to be admitted through the ER there, but it was a psych ER in the early morning and it was really fine and a non-event. My friend who came with me could stay with me the whole time until I went to the unit.
The general experience I had was very similar no matter where I was:
I got a shared room. I can sleep through anything, so this was not an issue, but I can see that it could be hard if you are disturbed by sharing a room with other people. The bathroom had a curtain and not a door, which was hard to get used to. There was a laundry and a nurse could go with me while I washed my clothes.
There are groups and activities throughout the day. Goal setting, arts and crafts, CBT or DBT thinking/worksheets, group therapy, coping strategies, relaxation/meditation exercises, time to walk laps in the hallway. Occasionally some are good, but mostly they are boring. Short term psych hospitalization is serving a lot of different people with a lot of different issues , I think. Nowhere I have been required groups and instead I could sleep or read or write or do crossword puzzles with a crayola marker. Usually a doctor would talk to me once a day and a nurse would talk to me once a shift. Sometimes it has been helpful but sometimes I felt they were too busy or distracted to really listen. The people caring for you are humans with their own issues, for better or worse. I had a get weighed on the unit in front of other patients once and when I objected due to past eating disorder issues, the nurse seemed as though she could not possibly understand why anyone under an incredible amount of stress wouldn't want to be weighed in front of a bunch of other people they didn't really know. I wanted to scream at her.
There is a strong push for meds in my experience, but when I have not wanted them, I did not feel forced to take or start anything. Through hospitalization I have been able to try medicines that are not "standard" treatment for depression (ritalin and ketamine). I did have a hospital psychiatrist change the meds a GP had started me on when I was just too spun out to question the GP. Looking back, I feel like the meds from the psychiatrist made more sense.
Each time I stayed between 5-7 days. There is a social worker there to try and help set up some supports for when I left. Making sure I had a safety plan, knew about my doctor's appointments, perscriptions, etc. These are things I generally already had a grip on. But it seemed to me that if you don't already have these things, they will help you set them up before you leave.
Good luck with everything.