Any particular reason why Senators serve six years and most other elected officials serve four?

Answer 1

Actually, no federal officials have the same term. The reason they're different is because the founders wanted the House to be indicative of popular opinion, the Senate to be less political and m roe deliberative, not having to worry about elections as often. The president at 4 years is a balance.

And it's worked remarkably well.

Answer 2

I like Jeff P's response.

Also, the Senators serving longer terms are not as subject to the whims of the voting public. In theory, they then can address more serious issues without being afraid of being voted out of office for their actions.