Good call on the silicone. That'll help keep your doors from sticking/freezing shut in the winter, too. Yes, we have that problem way down here below you. Changing the weatherstripping on the doors is a fairly easy task, too. You might want to get the part numbers for the leaky door strips from Deathrat, and run 'em through www.gmpartsdirect.com
, from my limited experience, they're the cheapest source for genuine GM parts. No overhead, no markup. If you read my last post about my ABS, you know what I mean!