The HD280s are really good in my opinion, my pair lasted for a long time. Maybe you should break them in for a several hours and it should have a significant change. Getting a good amp (I use something like this and an inexpensive one like this FiiO E5) and sound card (assuming you're on PC) would do wonders as well.

At the end of the day, it really boils down to what you enjoy and can afford. So goodluck with that man!

Well, I can't help with the TV/monitors, because there's no budget, but I would go this route w/ monitors:

Female RCA and female 3.5mm, FiiO E5 portable amp to use as in-line volume control optional, RCA Audio Cable Adapter for XBOX 360, and HD 201 headphones.

Then all you need is two RCA cables per console and HDMI cables.