Engine speed vs. throttle position/vacuum

[occupant]

I'm currently driving a 1997 Dodge Intrepid, 3.3/auto. I'm going to add a vacuum gauge to it at some point and wonder if it would really be neccessary. As it is, I drive the car as such that the rpm's stay right around 1500 during acceleration and cruise. Only in first gear do I need to go up to 1800-2000 to get it to shift to second, and only on level or uphill grades. At 1500rpm with minimal throttle input, once it hits fourth gear and goes into lockup, I can go 50mph. I don't need to go much faster but on the interstate I do get 2000rpm at 65mph which is at the bottom end of the torque peak for this engine.

I am just curious to know if this is the ideal driving style for this car or if I should try the vacuum gauge out and see if it allows for more efficient driving with higher rpms during acceleration? Or am I doing fine as is? I have yet to fill the tank twice to calculate mileage (too broke to afford it).