I know it's a bit expensive - but the P180 is one of the better (top 10?) cooling cases out there - plus it is nicely styled. It has a load of engineering around it as well, rubberized grommets for the hard drives, a rubberized psu cage, removable drive cages, drive rails - heck it even has a hiding place for spare parts. Not to mention the two zones of cooling - lower and upper, and the removable washable air filters.
Regardless, make sure you get a case with at least 2-120mm fans. This will help ensure good air flow. If you are building a budget system, you could do worse than Antec cases with included PSUs. Though it is generally better to buy a solid case and a solid PSU for exactly what you need.
A decision on a case is personal - it depends on what you like or don't like. Since you included the Sonatta - I will assume you do not like the windows, neon or space alien design aspects of some cases.
If you do choose the P180 (or P180B), You will not be disappointed. Do your research, and have fun.
Well I dont really know exact details about the SOLO but if it has enough space and the holes for extra fans then go for it. Remember that Air flow on the case is one of the most important things inside the case specially if you plan to overclock.