I remember FS4 let me go up to 300,000 feet or more. It was fun making a jet that weighs 700 lbs and has 20,000 lbs of thrust (not very realistic, I know), blasting off, and then trying to keep the plane under some semblance of control as you came back down. Right around 260,000 things started getting really bumpy, but if you were lucky you could get it back under control and land somewhere on the great expanse of green, even if it wasn't a runway. Anyone who enjoyed FS4 and misses tinkering with it should try X-Plane, it's a lot more fun and easy to mess around designing your own planes than any version of FS
later than 4, and the frame rates are smoother like 4 (although the scenery is way better).