Adding a demo panel of each hosting plan will help a lot chosing which plan to buy
This will be very helpful in case added
please think seriously about it

You are right.

by the way, you can check the websites of each control panel, like:

http://www.swsoft.com/en/products/plesk75reloaded/
http://www.cpanel.net
http://webmin.com/
http://www.directadmin.com/

I think the majority of them offer an online demo, or at least screenshots and feature lists
just my 2 cents