Wait…do you mean 24x18’ at the longest stretch of the L-shape? I think you’re gonna need bigger monitors. I’m no acoustics expert, but I’ve been told over and over by room designers that it takes power to form a usable low end image in a large space, because your speaker (and built in amp) have to have the ability to move air.
I posed this question to Wes Lachot when I was talking to him about building a facility: He was talking about the reason large mix rooms install $50,000 Augspurgers and the importance of accurately tuning them all the way down to 40hz. Figuring I had nothing to loose by asking him, I said ‘can’t you just use smaller monitors and sit closer to the speaker’? If I understood him correctly, he explained that with bass response, the low end image, and more importantly the accuracy of the low end image, it has less to do with your relative proximity to the speaker and more to do with the cubic volume of the room. And beyond there proper treatment and a good design.
Mid-high quality range, I really think JBL LSR’s and Yamaha HS series should be considered here. Both are moderately priced have subs that are tuned to match the system.
If you want my opinion on some of the higher end ones, I’ll share it, but it may not help much if you’re under $2,000 budget wise.
…about the original question ‘high end vs midrange’, the worth of it depends on what you’re doing. It depends on your client base, your workload, your genre (Broadcast, Film, Gaming, Music, Theater, Foley). High end Barefoots, ATCs, and Focals, and Genelecs, and Adams sound different. They’re distinctly more detailed, clearer, and make use of some pretty cutting edge technology. But (assuming you can afford them) are they better for you? Not necessarily.