Tools to measure in room response

Kal, thanks for your comments. I attempted to be as "rigorous" as possible with this somewhat crude method.

First I placed the SPL meter at the location where my head would be with normal listening. Obviously this required moving the listening chair to position the tri pod. Also I measured my ear hight from the floor when seated and set the meter at that same elevation. BTW, my RS instructions say to position the analog meter at 90 degrees from the sound source. A friend with the same model meter (but probably newer by several years) has instructions to point the meter at the source!?!

Then as I moved my speakers in 2" increments I found one distance where the aggregate deviation from the 1K reference was the lowest. So I then moved the speakers forward and backward by 1" from that point, measuring each. This was like focusing a telephoto lens and allowed me to position my speakers within an inch for smoothest response. I found this more satisfactory than I had been able to position by ear previously (although admittedly I had not tired so many positions).

Given your point on the small distance variations, I don't see how any other process could provide a better approximation.

K, you have received good advice so far.
I would like to add that the most musical in-room response is not a straight line in the treble range. Most listeners perceive a flat treble in-room response as bright-sounding.
A gradual roll-off starting around 12 KHz is correct for off-axis, far field listening in a room with standard furniture / carpets / curtains.
By off-axis I mean slight toe-in, as recommended by most manufacturers.
Adjust speaker tilt and toe-in to achieve a gradual slope, with no major peaks or valleys.
I hope this helps

To do this properly you will need software (RoomEQWizard works fine for "snapshopts", but I prefer TrueRTA as I can see the changes visually as I move things around), and a properly calibrated microphone along with a mic preamp.

If you are taking this project seriously, don't use the RS SPL meter, as it is well known that it is not accurate.

I use a portable phonic PPA3 RTA and achieve consistently good results.

Its built-in microphone is calibrated, you can store the data in your computer through an USB port and calculate the average of several room response graphs (just like John Atkinson does in Stereophile room response meausurements).
It comes with 31 band spectrum analyser, SPL reading, EQ setting calculations/suggestions, RT-60 calculator, phase checker, a built-in test tone generator and a test CD.
Last time I saw it cost U$ 500, a great investment if you really want your system to shine.

The learning curve is quick, in 30 minutes you are set to go.
In most systems I can find a much better loudspeaker positioning after 3-4 readings.
Usual disclaimer...

I tried the PAA3 and I currently use Fuzzmeasure. I find the sweep of PAA3 takes too long and very susceptable to ambient noise. Fuzzmeasure allows 1/3 octave to 1/48 octave smoothing with RT60 calcutalions at 1/3 octave. The sweep time and freq range is also adjustable. The curves from each measurement can be superimposed on the same grap so you can see the result of each change you do to the room/speaker.

PAA3 is useful in other ways and very portable. But for frequency response curve and reverb measurements, Fuzzmeasure is more precise and informative