Ask HN: Recommended hosting service that scales well

Apologies if this is sort of basic but does anyone have a good recommendation of hosting services for a small but growing webapp. I know if we throw enough money at this we can solve this problem very quickly but I want to be prudent and not break the bank unnecessarily while at the same time make sure the site doesn't crash every time we get a few thousand hits. I'm having a hard time finding a solid middle ground just by searching around the internet.

Thanks much for any pointers.

Best, A