Garmin eTrex Vista HCx is a lovely little handheld unit. Had mine for a year now and I love it. I upgraded from a slow-but-steady black & white Legend which is why I kept with the handy eTrex format. Sensitivity with the MediaTek chipset is fantastic - full satellite coverage in your living room!
The 60CSx has a bigger display, very reliable SIRFstar-III chipset, a few more bells and whistles. Its physically bigger than the Vista, but it also packs a helix-antenna which in theory is better than the Vista's patch-antenna.
If you don't need an electronic compass and barometric altimeter you can save a few $$s on either model by buying the eTrex Legend HCx or the 60Cx respectively. With a dash mount the 60CSx/Cx is an okay satnav for the car, though a Nüvi is better.
For the handheld units you'll need to buy either Topo maps for hiking or City Navigator for driving. Remember to factor in the cost of maps.
I have a Nüvi 660 for the car. Again, I'm very happy with it. It came with City Navigator Europe 2008 NT. The US models obviously come with CN US 2008 NT instead. You can load Topo maps onto a Nüvi but its not waterproof and not great as a handheld.
Which brings us to the latest, greatest offerings from Garmin.
The Nüvi 5xx series is apparently waterproof and ruggedized making it a better hiking option than previous Nüvis. Still primarily a car/motorbike navigator though.
And finally the Oregon series - touchscreen handhelds which are aimed primarily at the outdoor users. Add a car mount and City Navigator and with their touchscreens I bet they'd be just about the best all-round compromise models out there.
I'm very happy with the Vista HCx and the Nüvi 660. I hike, geocache and drive a decent amount and I've got all the bases covered.