I don't exactly fly a big airliner, but I can definitely say I know that feeling you get. Everytime I fly a larger airplane, there's an interesting feeling of excitement with a little anxiety mixed in. I know I'm capable of handling the airplane, but it is still exciting. The first time I flew a Tiger (my first airplane), it was exhilarating. I got the same feeling the first time I flew a Cessna 310, King air 90, and now the King Air 350. As I get the power up to takeoff setting, usually about the 80 knot crosscheck, I get this anxious feeling with a lot of excitement because I'm hurtling down the runway at a high rate of speed. I must say, it is the same feeling regardless of the airplane (so far), you are just playing with bigger numbers.