Question: I wish to distinguish between items that are preferred and items that are good, but not necessarily preferred. Is there a word to describe the latter?

Answer: 
I would go with "[acceptable](http://www.ldoceonline.com/dictionary/acceptable)".

> 
> good enough to be used for a particular purpose or to be considered satisfactory
> 
> 
> 

So, a sentence might read:

> 
> The preferred option is "Solution A" but "Solution B" is *acceptable*.
> 
> 
>
Here's a suggestion--**suboptimal**. From **Collins**:

**suboptimal** (sʌbˈɒptɪməl) or suboptimum (sʌbˈɒptɪməm) 

adjective not as good as possible, not quite optimal

Crossword puzzle bloggers reviewing puzzles that could be better often say that the puzzle contains **suboptimal fill**.