“Seemed like a good idea on paper.”
“Some days, a killing spree seems like a good idea.”
“Good ideas rarely seem like good ideas at their inception, that's what stops the majority of people from having them”
“It had seemed like such a good, such a romantic idea, to drive and not stop for gas.”
“That still seemed like a good idea, back on failed attempt number three.”
“Immortality seems like a good idea, until you realise you're going to spend it alone”