For biographical data, see the official directory of Congress, Congressional Directory, which has been published since 1888 by the Joint Committee on Printing. Or use the Congressional Biographical Directory which has a simple search template which contains information on legislators back to 1774.
For more details about current legislative activities Congress.org website to track the committee assignments, bill sponsorships and other details of each Senator or Representative.
Westlaw includes a database for The Congressional Staff Directory (congstaff-dir). It has detailed profiles for U.S. Congressional committees, subcommittees, task forces, caucuses, etc. as compiled by the CQ Press staff.