といいのに

といい hopes about an outcome still open (明日あした晴はれるといいね, sayable before anyone checks). といいのに needs a contrary fact to push against, once the forecast says rain.

のに normally says one thing despite another. といいのに swallows the second half, leaving the wish counterfactual.

ばよかった regrets a past act or omission, always in the past (言いってくれればよかったのに). といいのに wishes the present were otherwise, with nothing anyone could have changed.

〜ば〜のに names the outcome the unmet condition would produce (もう少すこし安やすければ買かうのに). といいのに puts いい there instead, naming no outcome, just wanting the condition itself.

たらいい offers an option worth taking (そうしたらいいよ). The same たら under いいのに loses that advice, since のに says it isn't there.

といいのに wishes against a fact you already know is false (早はやく終おわるといいのに). ないものだろうか wonders if a still-open chance might come through instead (見みつからないものだろうか).

休やすめばいい recommends resting as the thing that would settle it. 休やすめばいいのに complains that the listener isn't resting, and probably won't.