Personally, I have access to eight sites, but only have funds in two of them. IMO, if you do not plan to play at any (or all) sites which you have access to, then open an account at Moneybookers (or similar if possible) and withdraw your funds, keeping them in one place. There may be a time when you decide to take a break from poker - I know I have - and this method has simplified my money management. If you decide to use this method, note that you must make a deposit (the minimum will do) to a site before you can withdraw funds. But also, you do not have to produce ID of any kind to make a withdrawal - just your e-mail address (I have set up a special address for this purpose). I have not had any problems with any site since using this method.

If you are not going to play at a site for any length of time, then why keep funds there?