I had the same problem with an off/on coolant leak, could smell it but couldn't see it. Once and awhile found a puddle of coolant on garage floor.
Check right rear of engine where coolant lines go over valve cover, my lines rubbed against the valve cover causing a pin hole leak in one line.
New lines have a bend in them routing off the valve cover.
If problem persists after changing pressure cap check this.
I will, thanks. So far it seems like the cap is doing its job. One day I did find 2 drips but they were under where the front of the engine would be. I had remembered your post about the friction damaging those hoses and so I put UV dye in and checked them first (I think maybe mine are a revised version?) and then all around the engine and the engine compartment from both above and below (using a proper UV light and all) - nothing.
The only reason I found what I found around the radiator cap is because I had spilled some dye when I was putting it in (then I tried to rinse it away, forgetting what the dye was for, and made a huuuuuge green lake in my work parking lot) and later on I took it all to a wash bay and completely rinsed it down. Two days later, I was still smelling coolant but not seeing anything anywhere, so I did another UV light search and found nothing again...but then I noticed that around the cap (where I had been careful to completely hose away all traces of the dye) were more traces of the dye itself with no coolant left (had all burnt off, hence the odour I'm sure) leaving some crusty red stains.
I ordered a new cap (had to come from Tennessee...not one dealership in Canada had it, per the parts guy at Leggat Chev in Burlington) and when I put it on, I noticed that both the rubber seals on the old one looked very flattened out or squished; and also, there was a large amount of coolant present in the outer shell of the cap where it shouldn't ever get (the spinning part that threads onto the water outlet, but is above where the seals are so it never sees coolant). It seems reasonable that a radiator cap would start to crap out after 7 years...I seem to recall the old-fashioned ones would need replacing periodically, so why not these apparently rare, fancy-pants ones as well? LOL
It's been a few days now and I'm not noticing anything so far. There's no odour of coolant (I could smell it when I was exiting the driver's door, didn't even have to be close) unless I get right up near to coolant components and put my nose within inches of them (i.e. hoses, pressure cap, the overflow tank) and even at that range it is extremely faint; so, I'm THINKING I got it right. I'm going to go another few weeks and see how it goes. Then I have to decide if I want to flush the system for the second time within 15,000km (wish this happened BEFORE I had the coolant flushed) to get the dye out.