Thanks a lot for your feedback.  We have OWD set to public read/write and restrict field level access (to certain fields) by field security. Also seperate record types (page layout) is used to segregate different users from what they can see (UI perspective).  Now one of the issue - how to restrict users from seeingaccounts that have a specific record type say "Key Account".  This type of account is owned ony by Executive and Sys Admin.  

We have different Account Page layout based on "Key Account" record type. User profile that is assiged this record type, can view the Account fields.   While we can restrict the user from seeing certain fields, Is there a way for us to completely block access to Account whose record type is set to "Key Account".

One way, I can think of is to set OWD to private (we would rather not if feasible). And set account sharing rule that will share all account except that record type. Then assign this rule to "Role & Subordinate" - CEE role and below. That way, users with "CEO" Role and below can access all accounts (as seen by the CEO Role) but not the "Key Account"s.  CEO is the only person who is the owner of this "Key Account". Since OWD is set to private, he can see the account. Will this work?   or is there any other way?