On the surface, both 駄目{だめ} and 良くない{よくない} seem to have a similar meaning and use - both are adjectives of some kind and both seem to mean "not good".
駄目{だめ} is defined as a bad state or condition; ineffective as in wasteful of effort; a situation or condition upon which nothing can be done; a forbidden action :
- 暑さ{あつさ}で食べ{たべ}物{もの}が駄目{だめ}になる - Food turn bad in the heat
- いくら頼んでも{たのんでも}駄目{だめ}だ - It is useless no matter how much you ask
- これ以上{いじょう}歩け{あるけ}と言われても{いわれても}とても駄目{だめ}だ - It is impossible although it is said you can walk further
- ここでタバコを吸って{すって}は駄目{だめ}だ - It is forbidden to smoke here
良くない{よくない} from the adjective 良い{いい} is a generic way to say good :
- いい景色{けしき} - Beatiful landscape
- 割{わり}のいい仕事{しごと} - A fair job
- 態度{たいど}がいい - The attitude is good
- 君{きみ}に会えて{あえて}よかった - It was nice to meet you
- 帰って{かえって}もいい - You can leave (go home)
If we looks at your examples:
何処も{どこも}良くない{よくない}です
Using 良くない{よくない} in this sentence it means that no places are good. If we replace it by 駄目{だめ}, the meaning changes to "everywhere is bad". Note that 駄目{だめ} is also much more intense in meaning than 良くない{よくない}.
家族{かぞく}は最近{さいきん}あまり運{うん}が良くない{よくない}
This sentence means something like "the family isn't very lucky lately". In this situation, it is impossible to replace 良くない{よくない} with 駄目{だめ}. 駄目{だめ} is a name whereas 良くない{よくない} comes from an adjective - it would not fit in this sentence. To say your luck is bad you'd say 運{うん}が[悪い]{わるい}. 運{うん}が駄目{だめ} would mean "I am bad at luck". It does sound right.
駄目{だめ}なホテルでした
This a proper use of 駄目{だめ}. 良くない{よくない} could also be used. However, 良くない{よくない} is much more indirect and polite. It would not carry the same meaning.