Well, the best monitors in the world can still suck in a bad room
Your best route is probably a combination of treatments and getting a really accurate reading of the total response at mix position(you are really only going to be able to correct for a single point in the room). There are some very clean digital signal processors on the market, and even the inexpensive Behringer UltraDrive 2496(not the LE version) can do some very customizable EQ to tame room issues. Having said that, at the end of the day, a good set of speakers(which you never mentioned) and a decent set of headphones(for checking the bottom 2 octaves) will likely do fine, once you "learn" your room(and whatever issues it may have).
You can learn a lot about your room by bringing up the signal Generator plugin on a mono aux track, set a reasonable volume with a 1K sine wave, and then slowly lower the frequency and have a pad and pencil handy. As the frequency moves downward, make notes if any suddenly gets louder, or softer. Those frequencies are where your listening setup has issues(listening setup being the combination of the speakers, the room, the treatments and anything that might contribute physically, like a big desk surface). I bet when you get down below 200Hz, you will probably find at least 2 frequencies that nearly disappear, and 2 others that poke out a lot(on the order of 10-14db in the few small rooms I have measured). Cutting where you have peaks is fairly easy with a parametric EQ before your speakers, but boosting to fill the nulls is not as easy(a couple of 10-14db boosts would chew up a ton of headroom in your speakers). Nulls are better solved with acoustic treatment, moving things around(sometimes inches can make big changes).