Lee, I'm not an expert, but it needs to be more of a work room than a chapel. It needs areas or work stations for the different issues like missions, church families, illness, church ministries, etc. Information should be up to the minute. Pictures on the wall of people and needs that are prayed for regularly are helpful. A map showing where missionaries are serving is good as well.
The first pray station should be for worship and have some kind of prayer guide that includes praise and confession.
If people will be coming their around the clock; it must have a well lit outside entrance with a gook lock.
Our's is one room with a variety of chairs & even a small sofa to sit. It also has a kneeling alter. Also a stereo/CD player for music. It is open when the church is open. A group of us usually meet on Sat. mornings for group prayer. It has a small reference library and a prayer wall/bulletin board for requests & praises. Nothing fancy, but it works and we have seen specific answers to some of our prayers!
I know of a church that is in an old bank and the vault is still there, so they have turned it into a prayer room. It's very cool--Subdued lighting and comfy furniture, open all the time and manned by folks who are called to intercede for others. This church is a large church and the vault provides a smaller, quieter spot to pray and/or be prayed for.
Our prayer room is similar to a small study. It has a place to kneel and the shelf in front has a large Bible on it. There is an armchair, a small desk with a chair and a sofa for a couple of people. There is a small CD player for music.
It is a beautiful room, but on the dark side, which I think is conducive to prayer.
There are also pre-printed prayer cards (suggested prayers).
Then we have blank prayer cards that people complete Prayer Requests. Then on the other side, we have Praises. It is nice when someone comes in and changes their Request to a Praise.