I've noticed that there are multiple ways of providing or asking for a recommendation in Japanese.
The sentence structures I'm talking about are as follows:
したらいい
すればいい
したほうがいい
In almost all situations I see these they get translated as "should do" and they all seem to share a common structure of equating the done action as being "good" but is there a difference in nuance or are they interchangeable?
First, I will discuss the difference between 「～～したらいい」 and 「～～すればいい」.
The difference between the two expressions stems directly from that between 「たら」 and 「れば」. Both practically mean the same thing, but as for nuance, 「たら」 is more informal and conversational than 「れば」. The difference might not be a significant one in many situatins, but it sure exists.
Thus, 「したらいい」 and 「すればいい」 are interchangeable only for the meaning. Careful speakers might also (try to) make alterations with the other words and phrases within the sentence to reflect the change in formality between 「たら」 and 「れば」. Whether or not those alterations are necessary would totally depend on the actual sentences.
Moving on to the difference between the two expressions I just discussed above and 「～～したほうがいい」. There is a difference in meaning/usage here even though it might not always be reflected in the English translations - "You should ~~", "You'd better ~~", etc.
「したほうがいい」 is used to give or ask for a recommendation when you are basically choosing between TWO (2) possible actions. This would mean choosing between "Action A and Action B" or between "Action A and not taking Action A".
「したらいい」 and 「すればいい」 can be used when the number of possible actions to take is between two and infinity.
Thus, the interchangeability is limited between 「したほうがいい」 and the other two.
That's complicated... Although they can sometimes mean the same thing, they all have their own specific way to be used that could in some cases not be interchangeable.
すれば is for more imaginary/hypothetical/have yet to happen situations.
こうすればいけるかもしれない。
したら is for more for facts/occurred/related to a specific individual situations.
掃除したらきれいになるよ。
した方がいい is the one that can be used to compare 2 possibilities.
青いやつより、赤いやつにした方がいい。
This could also be a good read for you: http://tinyurl.com/jzt5leh
