About two weeks ago I was in both the Senator and Business LH lounges at IAD, and they both had the same food and were both very crowded, though the Senator had a small seating area set off for First Class ticketholders only (which was empty). In fact, I really didn't notice much difference except the wines may have been better in Senator. I went over to the UA GlobalFirst lounge instead (I was flying GF on UA) which had better champagne and food and was less crowded, though a bit threadbare.