One last month, one yesterday, both planned from KLAF to KCGF. Last month, I had airline tix IND-ORD-CLE as backup (primary actually). Forecast all week leading up to that morning was looking great. I was feeling slightly behind on planning the night before, but nothing bad. That morning, an AIRMET for icing was in place for the first half of my trip. I delayed a bit but then decided to scrub and head to IND. Not real happy about it, because is looked totally clear. On the 1hr drive to IND, it looked great. On the flight from IND to ORD, it still looked good. And ORD to CLE, clear. Not happy. But one of my friends who is a CFI said that's exactly what you want; Said I made a good decision. So I agreed with that. This weekend my back up was to drive. I needed to be in Cleveland before 1p, but I was not back in town from work until 7:30p the night before, and had to unclog a sink and do other crap before the next morning. Needless to say I was tired. But the forecast had looked OK over the week. I had to watch approaching forecast rain early Sun/late Sat, but that was it. But the day before, the Cleveland forecast started to look iffy. Not a show stopper, but deserved respect. Windy, cloudy, maybe snow east of my destination. Decided not worth it, gonna drive. Well as we drove that morning, the weather looked great. About 100 miles away, the sky started closing up. Ceilings got lower and lower and about 20 miles away snow started. About 10 miles away, visibility on the highway was 1/8 mile. I knew I had made a good decision. What I learned is to just trust my training and keep the go/no-go a simple decision. Sure, I might miss opportunities to fly, enjoy, and learn...but I'll also miss opportunities to get myself in a jam and possibly one I can't get myself out of. Both decisions had the exact same disappointment at the time they were made. Both seemed like a weak move at the time. The first could have reinforced the wimpiness of my choice were it not for some new pilot-to-experienced pilot debriefing. The second reinforced the rookie "wisdom" of my choice. I hope this helps someone.