If you're serious about multichannel music, you're really putting yourself in a box. For a while I had matching L-C-R speakers but very non-matching surrounds, and that was just fine on movies. At that point I had something like 8:1 investment ratio in the L-C-R vs the surrounds. Then I got a few DVD-As and discovered that the good ones REQUIRE matching surrounds to be sensible. To an interesting degree this means that you have to have matching speakers, which does limit your choices.
I think I'd agree, though, with some of the others - buy into a product line that you like for music and then add the surround channels later. I won't make a recommendation but rather mention what I've used. My first system used 4 ProAc Tablette 50s and a ProAc CC1 - and it had to have a sub because the little things just don't go down below 50-60 Hz. You can get a setup like this for around your $5K, including the sub but not stands. (The Tablette 50s have been replaced by the Tablette 8, which is even more impressive.)
My current system uses Martin Logan Odyssey / Cinema / Scenarios / Descent and is far outside your $5K budget. You might start with something like Scenarios / Cinema / Grotto and then add either Script surrounds or upgrade the mains to another ML (Aeon / Ascent etc) and repurpose the Scenrios as surrounds.