What size room have you got? is there lots of furniture? is it quite reflective? (can you hear much reverb?)
These are the questions you have to ask as every room is different and will need to be treated according to it's needs (as well as the monitors)
However that said it seems you are going to be putting a lot of bass in there with that set up so I would focus on getting the low-end section covered first and then build from there.
I use the GIK acoustics myself they offer high quality aren't the most expensive on the planet (more than the foamy auralex stuff but this is designed for proper broadband treatment not just sucking out the high end) They also offer a lot of advice and have steered me in the right direction. Just fire them an email and give them the info of your room etc and they'll help you out.
I would go for something like the GIK 244 panels for your first reflection points L & R first of all. that will tighten up your stereo image, help with low end and offer some absorption for higher frequencies (just to a lesser degree as it focuses on low end) These can be bought for about £150 but are well worth the investment.
Again hit them up on their website for more info
