What does the dispatch release say?
But seriously, for GA flying: fltplan.com
I've always been surprised by how much people get into weather planning for what seems to be a relatively simple flight. I feel like METARS, TAFS, PIREPS, icing and convective forecasts and maybe winds aloft depending on what kind of flying you're doing cover it pretty well. Guys who spend 10+ minutes studying radar charts and whatever else on a computer in an FBO are baffling to me. Yeah, you get an idea of things and trends, but if the issue is that much in doubt then you either need a better airplane, an alternate plan or just wait for another day.
There's only so much practical information you can absorb from weather services. The fltplan.com route briefing printout covers everything you really need and more. It's seriously as good as an airline dispatch release (or as good as you're going to get for free in GA).