Hm, I don't know about the doors in the Enclave, but I assume to open them is pretty much useless, as there are no hints, rumours or whatever that indicate it was supposed that something is behind those doors. Sometimes closed doors are just that - closed doors... But if you find anything interesting behind them, tell me :-) .
The door in Drashdae is a different thing though. Rumour has it that the Czerka office should be behind that door. I made the connection from the deleted (empty!) Czerka office to the Drashdae floor. The other way around is a different matter though, as the walkmesh (?) doesn't let you enter the appropiate area to transit to the Czerka office, unfortunately. (Some modders worked on the Czerka office module, but never finished it.) As other posters pointed out that problem could be solved with a computer console though. As it is now, one only sees an anattractive black box (if I remember correctly) behind the Drashdae door. So its better to leave it closed :-) .
"I really had it in me to become a loser - as usual, I did not make it!" - Otto Waalkes