I got the matching SR9080 bi-pole surrounds and have been very pleased with the whole setup (you don't necessarily need the matching surrounds though). They hang flush against walls so are pretty unobtrusive.
5.1 or even 5.0 of course.
3.0 or 3.1 are also really good option for you.
4k can buy quite good 3 front speakers and something to run them (that part is hard for me as I run everything from a PC and not really into a processor/receiver market).